The chromosomal high mobility group box-1 (HMGB1) protein acts as a proinflammatory cytokine when released in the extracellular environment by necrotic and inflammatory cells. In the present study, we show that HMGB1 exerts proangiogenic effects by inducing MAPK ERK1/2 activation, cell proliferation, and chemotaxis in endothelial cells of different origin. Accordingly, HMGB1 stimulates membrane ruffling and repair of a mechanically wounded endothelial cell monolayer and causes endothelial cell sprouting in a three-dimensional fibrin gel. In keeping with its in vitro properties, HMGB1 stimulates neovascularization when applied in vivo on the top of the chicken embryo chorioallantoic membrane whose blood vessels express the HMGB1 receptor for advanced glycation end products (RAGE). Accordingly, RAGE blockade by neutralizing Abs inhibits HMGB1-induced neovascularization in vivo and endothelial cell proliferation and membrane ruffling in vitro. Taken together, the data identify HMGB1/RAGE interaction as a potent proangiogenic stimulus.

14 C-PNU 145156E binds immobilized GST-Tat with a dissociation constant 5 times higher than heparin and is unable to bind GST-Tat R49/52/53/55/56/57A . Although heparin was an antagonist more potent than suramin, modifications of the backbone structure in selected suramin derivatives originated Tat antagonists whose potency was close to that shown by heparin.In conclusion, suramin derivatives bind the basic domain of Tat, prevent Tat/heparin and Tat/cell surface interactions, and inhibit the biological activity of extracellular Tat. Our data demonstrate that tailored polysulfonated compounds represent potent extracellular Tat inhibitors of possible therapeutic value.

Angiogenesis, the process of formation of new blood vessel from pre-existing ones, is involved in various intertwined pathological processes including virus infection, inflammation and oncogenesis, making it a promising target for the development of novel strategies for various interventions. To induce angiogenesis, angiogenic growth factors (AGFs) must interact with pro-angiogenic receptors to induce proliferation, protease production and migration of endothelial cells (ECs). The action of AGFs is counteracted by antiangiogenic modulators whose main mechanism of action is to bind (thus sequestering or masking) AGFs or their receptors. Many sugars, either free or associated to proteins, are involved in these interactions, thus exerting a tight regulation of the neovascularization process. Heparin and heparan sulfate proteoglycans undoubtedly play a pivotal role in this context since they bind to almost all the known AGFs, to several pro-angiogenic receptors and even to angiogenic inhibitors, originating an intricate network of interaction, the so called “angiogenesis glycomic interactome”. The decoding of the angiogenesis glycomic interactome, achievable by a systematic study of the interactions occurring among angiogenic modulators and sugars, may help to design novel antiangiogenic therapies with implications in the cure of angiogenesis-dependent diseases.

Chorioallantoic membrane (CAM) and chorioallantoic fluid (CAF) of the chick embryo were studied for the presence of immunoreactive and biologically active basic fibroblast growth factor (bFGF) from Day 6 to Day 18 of incubation. An immunoreactive M(r) 16,000 bFGF-like molecule was detected both in CAM and in CAF. This molecule was identified as bFGF on the basis of its molecular weight, its affinity for heparin, and its capacity to induce plasminogen activator production in cultured endothelial GM 7373 cells. The levels of biologically active and immunoreactive bFGF vary in CAM and CAF during embryonic development, maximal concentrations being observed between Days 10 and 14 of incubation. At all time points investigated, absolute concentrations of bFGF were significantly higher in CAM (ranging from 25 to 183 ng/g of wet tissue) than in CAF (ranging from 0.2 to 4 ng/ml). In a parallel series of experiments performed at Day 8 and evaluated at Day 12 of chick embryo development, human recombinant bFGF and neutralizing anti-bFGF antibody were investigated for their capacity to affect the vasoproliferative processes of the CAM. The two molecules either were applied onto the surface of the CAM or were injected into the allantoic sac. When bFGF or anti-bFGF antibodies were absorbed on methylcellulose discs and applied on the top of the CAM, they exerted a strong angiogenic or anti-angiogenic effect, respectively. On the contrary, when bFGF or the corresponding neutralizing antibody was injected into the allantoic sac, no modifications of the vasoproliferative processes of the CAM were observed at either the macroscopic or the microscopic level. These results provide evidence indicating that endogenous bFGF has a rate-limiting role in the vascularization of the CAM during chick embryogenesis. bFGF located within the CAM, rather than that present in the CAF, appears to be involved in this developmental process.

Angiogenesis plays an important role in tissue remodeling and repair during the late phase of inflammation. In the present study, we show that human dendritic cells (DC) that matured in the presence of anti-inflammatory molecules such as calcitriol, PGE2, or IL-10 (alternatively activated DC) selectively secrete the potent angiogenic cytokine vascular endothelial growth factor (VEGF) isoforms VEGF165 and VEGF121. No VEGF production was observed in immature or classically activated DC. Also, the capacity to produce VEGF was restricted to the myeloid DC subset. When implanted in the chick embryo chorioallantoic membrane, alternatively activated DC elicit a marked angiogenic response, which is inhibited by neutralizing anti-VEGF Abs and by the VEGFR-2 inhibitor SU5416. Therefore, alternatively activated DC may contribute to the resolution of the inflammatory reaction by promoting VEGF-induced angiogenesis.