Angiogenic factors produced by monocytes-macrophages are involved in the pathogenesis of chronic inflammatory disorders characterized by persistent angiogenesis. The possibility was tested that interleukin-8 (IL-8), which is a cytokine that is chemotactic for lymphocytes and neutrophils, is also angiogenic. Human recombinant IL-8 was potently angiogenic when implanted in the rat cornea and induced proliferation and chemotaxis of human umbilical vein endothelial cells. Angiogenic activity present in the conditioned media of inflamed human rheumatoid synovial tissue macrophages or lipopolysaccharide-stimulated blood monocytes was equally blocked by antibodies to either IL-8 or tumor necrosis factor-alpha. An IL-8 antisense oligonucleotide specifically blocked the production of monocyte-induced angiogenic activity. These data suggest a function for macrophage-derived IL-8 in angiogenesis-dependent disorders such as rheumatoid arthritis, tumor growth, and wound repair.

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Tumor necrosis factor a and interleukin 1 stimulate the human immunodeficiency virus enhancer by activation of the nuclear factor cB ( ABSTRACTBinding of peptide hormones to surface membrane receptors leads to the transcription of specific genes within relevant target cells. How these signals are transduced to alter gene expression is largely unknown, but this mechanism probably involves a sequence of enzymatic steps that activate factors in the nucleus that modulate transcription. We now demonstrate that two different peptide hormones, or cytokines, stimulate the human immunodeficiency virus enhancer, and this effect is mediated by nuclear factor (NF) KB (nuclear factor that binds the K immunoglobulin light chain gene enhancer). These cytokines, tumor necrosis factor a and interleukin 1, act on multiple cell types and represent the only naturally occurring activators of this transcription factor among eight cytokines examined. Although NF-KB binding can be stimulated by phorbol 12-myristate 13-acetate, tumor necrosis factor a acts through an independent mechanism, inducing NF-KB binding in HT-2 cells, which did not show increased binding in'response to phorbol 12-myristate 13-acetate, and causing superinduction in Jurkat T-lymphoma cells. Tumor necrosis factor a is also a more selective activator of T cells than phorbol 12-myristate 13-acetate, having no effect on lymphokine production in EL-4 cells at the same time it induces NF-KB. These findings suggest that human immunodeficiency virus gene expression can be induced in T cells without activating lymphokine secretion and that the role of these cytokines in the activation of latent human immunodeficiency virus infection deserves further clinical evaluation. Finally, this link between binding at the surface membrane and stimulation of a specific transcription factor should help derme intermediates for these cytokine activation pathways.

In this study, we demonstrate that the CXC family of chemokines displays disparate angiogenic activity depending upon the presence or absence of the ELR motif. CXC chemokines containing the ELR motif (ELR-CXC chemokines) were found to be potent angiogenic factors, inducing both in vitro endothelial chemotaxis and in vivo corneal neovascularization. In contrast, the CXC chemokines lacking the ELR motif, platelet factor 4, interferon ␥-inducible protein 10, and monokine induced by ␥-interferon, not only failed to induce significant in vitro endothelial cell chemotaxis or in vivo corneal neovacularization but were found to be potent angiostatic factors in the presence of either ELR-CXC chemokines or the unrelated angiogenic factor, basic fibroblast growth factor. Additionally, mutant interleukin-8 proteins lacking the ELR motif demonstrated potent angiostatic effects in the presence of either ELR-CXC chemokines or basic fibroblast growth factor. In contrast, a mutant of monokine induced by ␥-interferon containing the ELR motif was found to induce in vivo angiogenic activity. These findings suggest a functional role of the ELR motif in determining the angiogenic or angiostatic potential of CXC chemokines, supporting the hypothesis that the net biological balance between angiogenic and angiostatic CXC chemokines may play an important role in regulating overall angiogenesis.Angiogenesis, characterized by the neoformation of blood vessels, is an essential biological event encountered in a number of physiological and pathological processes, such as embryonic development, the formation of inflammatory granulation tissue during wound healing, chronic inflammation, and the growth of malignant solid tumors (1-5). Neovascularization can be rapidly induced in response to diverse pathophysiologic stimuli. Under conditions of homeostasis, the rate of capillary endothelial cell turn-over is typically measured in months or years (6, 7). However, the process of angiogenesis during normal wound repair is rapid, transient, and tightly controlled. During neovascularization, normally quiescent endothelial cells are stimulated, degrade their basement membrane and proximal extracellular matrix, migrate directionally, divide, and organize into new functioning capillaries invested by a basal lamina (1-5). The abrupt termination of angiogenesis that accompanies the resolution of the wound repair suggests two possible mechanisms of control: a marked reduction in angiogenic mediators coupled with a simultaneous increase in the level of angiostatic factors that inhibit new vessel growth (8). In contrast to neovascularization of normal wound repair, tumorigenesis is associated with exaggerated angiogenesis, suggesting the existence of augmented angiogenic and reduced levels of angiostatic mediators (3, 9). Although most investigations studying angiogenesis have focused on the identification and mechanism of action of angiogenic factors, recent evidence suggests that angiostatic factors may play an equally important role in the control of neova...