TNF and diabetic retinopathy: However, in chronic pathological conditions such as diabetic retinopathy, microglia release excessive pro-inflammatory chemokines, including C-C motif chemokine ligand 2 (CCL2) and CCL3 or cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interferon gamma (IFN-γ), which promote disease progression [4,6,7].