CCL2 and diabetes mellitus: The BRB is also challenged in diabetes, as microglia respond to high glucose with a pro-inflammatory phenotype characterized by Iba1 overexpression, NF-κB activation, secretion of pro-inflammatory molecules (e.g., TNF-α) and chemokines (e.g., MCP-1 that can stimulate the arrival of leukocytes into retinal tissues, as observed in diabetic mice) [104].