Macrophages activation leads to high sensory and sympathetic innervation joint to angiogenesis in an arthritic inflammation murine model.182 Macrophages, neutrophils, T-lymphocytes, and mast cells express NGF.183,184 In damaged nerves, macrophage-derived IL-1β induces the synthesis of NGF in non-neuronal cells.175 There are no studies showing that neurotrophins released by tumor-associated leukocytes contribute to tumor innervation and neurogenesis in cancer, but it is hypothetically possible.178,180. Here, BDNF is linked to cancer.