IL6 and major depressive disorder: The role of cytokines as neuromodulators in the epileptic and depressive brain is based on the results of studies in humans and experimental animals; blood serum and cerebrospinal fluid (CSF) levels of cytokines (IL-1ra, IL-1β, IL-6, IL-17) are increased in PWE [30, 31] whereas increased plasma levels of IL-1β have been specifically connected with epilepsy-associated depression [32].