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...

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Interleukin-6 (IL-6), also called 26-kd protein, hybridoma plasmacytoma growth factor, beta 2-interferon, or B cell stimulatory factor 2, is a recently described human cytokine with multiple growth and differentiation activities. Using a very sensitive bioassay based on the growth factor activity of this protein for B cell hybridomas, we found that IL-6 activity was significantly elevated in synovial fluid from patients with rheumatoid arthritis (RA) or other inflammatory arthritides, as compared with that in a group of patients with osteoarthritis. Moreover, IL-6 was detected in about one-third of the serum samples from patients with RA. In the latter group, we found a significant correlation between serum IL-6 activity and serum levels of C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antitrypsin, fibrinogen, and haptoglobin, which indicates that IL-6 is related to disease activity in patients with RA.

1. Recent studies have suggested that interleukin-6 is a major mediator of the acute-phase protein response in man. The aim of the present study was to investigate the relationships between the response of serum interleukin-6 to surgery, the type of surgical procedure performed and the response of serum C-reactive protein. 2. Timed venous blood samples were taken from 26 patients in five broad surgical categories (minor surgery, cholecystectomy, hip replacement, colorectal surgery and major vascular surgery). C-reactive protein and interleukin-6 were measured in each sample. 3. Serum interleukin-6 rose within 2-4 h of incision in all patients and the magnitude of the response differed among the various surgical groups. The response of interleukin-6 correlated (r = 0.80, P less than 0.001) with the duration of surgery. In contrast, serum C-reactive protein was not detectable after minor surgery (less than 10 mg/l) and the response of C-reactive protein did not differ among the more major surgical groups. The response of interleukin-6 showed a weak, but significant, correlation with the response of C-reactive protein (r = 0.67, P less than 0.001). 4. We conclude that serum interleukin-6 is a sensitive, early marker of tissue damage. In general, the greater the surgical trauma, the greater the response of serum interleukin-6 and the greater the peak serum concentration of interleukin-6. Our results are consistent with a role for interleukin-6 in the induction of C-reactive protein synthesis.

IL-12 is a central cytokine in the activation of inflammation and immunity and in the generation of Th1-type responses. Tumor-associated macrophages (TAM) from mouse and human tumors showed defective production of IL-12. Defective IL-12 production was associated with lack of p50/p65 NF-κB activation. TAM produced increased amounts of the immunosuppressive cytokine IL-10. Abs against IL-10 restored the defective capacity of TAM to produce IL-12. Our data suggest that during tumor growth an IL-10-dependent pathway of diversion of macrophage function can be activated into the tumor microenvironment and results in the promotion of the IL-10+ IL-12− phenotype of TAM. Blocking IL-10, as well as other immunosuppressive cytokines present in the tumor microenvironment, such as TGF-β, may complement therapeutic strategies aimed at activating type I antitumor immune responses.

Partial overlapping cDNA sequences likely to encode a novel human CC chemokine were identified from the GenBank Expressed Sequence Tag data base. Using these sequences, we isolated full-length cDNA encoding a protein of 96 amino acid residues with 20 -28% identity to other CC chemokines. By Northern blot, this chemokine was mainly expressed in liver among various tissues and strongly induced in several human cell lines by phorbol myristate acetate. We thus designated this chemokine as LARC from Liver and Activation-Regulated Chemokine. We mapped the LARC gene close to the chromosomal marker D2S159 at chromosome 2q33-q37 by somatic cell and radiation hybrid mappings and isolated two yeast artificial chromosome clones containing the LARC gene from this region. To prepare LARC, we subcloned the cDNA into a baculovirus vector and expressed it in insect cells. The secreted protein started at Ala-27 and was significantly chemotactic for lymphocytes. At a concentration of 1 g/ml, it also showed a weak chemotactic activity for granulocytes. Unlike other CC chemokines, however, LARC was not chemotactic for monocytic THP-1 cells or blood monocytes. LARC tagged with secreted alkaline phosphatase-(His) 6 bound specifically to lymphocytes, the binding being competed only by LARC and not by other CC or CXC chemokines. Scatchard analysis revealed a single class of receptors for LARC on lymphocytes with a K d of 0.4 nM and 2100 sites/cell. Collectively, LARC is a novel CC chemokine, which may represent a new group of CC chemokines localized on chromosome 2.

Chemokines coordinate many aspects of leukocyte migration. As chemoattractants they play an important role in the innate and acquired immune response. There is good experimental evidence that N-terminal truncation by secreted or cell surface proteases is a way of modulating chemokine action. The localization of CD26/ dipeptidyl peptidase IV on cell surfaces and in biological fluids, its primary specificity, and the type of naturally occurring truncated chemokines are consistent with such a function.We determined the steady-state catalytic parameters for a relevant selection of chemokines (CCL3b, CCL5, CCL11, CCL22, CXCL9, CXCL10, CXCL11, and CXCL12) previously reported to alter their chemotactic behavior due to CD26/dipeptidyl peptidase IV-catalyzed truncation. The results reveal a striking selectivity for stromal cell-derived factor-1␣ (CXCL12) and macrophage-derived chemokine (CCL22). The kinetic parameters support the hypothesis that CD26/dipeptidyl peptidase IV contributes to the degradation of certain chemokines in vivo. The data not only provide insight into the selectivity of the enzyme for specific chemokines, but they also contribute to the general understanding of CD26/dipeptidyl peptidase IV secondary substrate specificity.

SummaryCytokine-stimulated human osteosarcoma cells (MG-63) secrete several related chemotactic factors, including the neutrophil-activating protein interleukin 8 (IL-8) and the monocyte chemotactic protein (MCP)-I. We describe the isolation and characterization of two novel monocyte chemotactic factors from this tumor cell line. Although these proteins copurified with MCP-1 and Ib8 on heparin-Sepharose, they could be separated by cation-exchange fast protein liquid chromatography and reverse-phase high-performance liquid chromatography. The corresponding 7.5-and 11-kD proteins were NH2-terminally blocked but were identified by sequencing peptide fragments. They showed a primary structure mostly related to that of MCP-1 and were therefore designated MCpo2 and MCP-3, respectively. These molecules can be dassified in a subfamily of proinfhmmatory proteins characterized by the conservation of cysteine residues. MCP-2 and MCP-3 are also functionally related to MCP-1 because they specifically attract monocytes, but not neutrophils, in vitro. The chemotactic potency (specific activity) was comparable for all three MCPs. Intradermal injection of these proteins in rabbits resulted in selective monocyte recruitment in vivo. Since tumor cells are good producers of leukocyte chemotactic factors, it could be questioned whether these molecules can indirectly control tumor growth by attracting leukocytes or whether they rather promote invasion by the secretion of proteases from the attracted cells.