Anti-CXCL15 monoclonal antibody, clone 07809

A major green tea component, epigallocatechin-3-gallate (EGCG), has been proven protective against lethal sepsis in experimental setting, but its protective mechanisms remain incompletely understood. Here, we provide evidence to support EGCG's capacities in stimulating G-CSF production and neutrophilia in vivo. In an animal model of sepsis, EGCG significantly elevated peritoneal levels of G-CSF and several chemokines (e.g., MCP-1/CCL2 and MIP-1 gamma/CCL9), and consequently increased peritoneal neutrophil numbers (neutrophilia) at a late stage. In vitro, EGCG divergently affected HMGB1-mediated production of several chemokines: reducing CXCL15 and RANTES/CCL5, but elevating G-CSF and MIP-1 alpha/CCL3 production by peritoneal macrophages. Similarly, it significantly induced the expression and secretion of G-CSF and MIP-1 alpha/CCL3 in human peripheral blood mononuclear cells. Based on our preliminary data, it may be important to search for anti-inflammatory and G-CSF-stimulating agents for the clinical management of inflammatory diseases.

Metastasis is the most devastating aspect of cancer, however we know very little about the mechanisms of local invasion, the earliest step of metastasis. During tumor growth CD11b(+)Gr1(+) cells, known also as MDSCs, have been shown to promote tumor progression by a wide spectrum of effects that suppress the anti-tumor immune response. In addition to immunosuppression, CD11b(+)Gr1(+) cells promote metastasis by mechanisms that are currently unknown. CD11b(+)Gr1(+) cells localize near fibroblasts, which remodel the ECM and leave tracks for collective cell migration of carcinoma cells. In this study we discovered that CD11b(+)Gr1(+) cells promote invasion of mammary carcinoma cells by increasing fibroblast migration. This effect was directed by secreted factors derived from CD11b(+)Gr1(+) cells. We have identified several CD11b(+)Gr1(+) cell secreted proteins that activate fibroblast migration, including CXCL11, CXCL15, FGF2, IGF-I, IL1Ra, Resistin, and Shh. The combination of CXCL11 and FGF2 had the strongest effect on fibroblast migration that is associated with Akt1 and ERK1/2 phosphorylation. Analysis of subsets of CD11b(+)Gr1(+) cells identified that CD11b(+)Ly6C(high)Ly6G(low) cells increase fibroblast migration more than other myeloid cell populations. Additionally, tumor-derived CD11b(+)Gr1(+) cells promote fibroblast migration more than splenic CD11b(+)Gr1(+) cells of tumor-bearing mice. While TGF beta signaling in fibroblasts does not regulate their migration toward CD11b(+)Gr1(+) cells, however deletion of TGF beta receptor II on CD11b(+)Gr1(+) cells downregulates CXCL11, Shh, IGF1 and FGF2 resulting in reduced fibroblast migration. These studies show that TGF beta signaling in CD11b(+)Gr1(+) cells promotes fibroblast directed carcinoma invasion and suggests that perivascular CD11b(+)Ly6C(high)Ly6G(low) cells may be the stimulus for localized invasion leading to metastasis.