CCL2 and infection: CCL-2 is a chemokine that is involved in recruiting monocytes and other immune cells to sites of injury or infection.46 Prior research has indicated that CCL-2 plays a role in neuroinflammation following TBI, contributing to BBB disruption and leukocyte infiltration into the central nervous system.47 The increase in CCL-2 levels among the former contact athletes may reflect a chronic inflammatory state induced by RHI, which could predispose these individuals to long-term neurodegenerative conditions.