CCL4 and metachromatic leukodystrophy: Astrocytes also participate in innate immune responses and neuroinflammation, which is a key driver of MLD disease progression, with elevated levels of CCL2, interleukin-1 receptor antagonist (IL-1Ra), interleukin 8 (IL-8), and CCL4 in the cerebral spinal fluid of patients with MLD (Thibert et al. 2016).