Serum interleukin-6 predicts cortisol release in acute stroke patients

Altered hypothalamo-pituitary-adrenal axis was reported in stroke patients; however, mechanisms responsible for this phenomenon are barely understood. Acute cerebral ischemia triggers interleukin-6 (IL-6) release into blood. Circulating IL-6 can stimulate hypothalamo-pituitary-adrenal axis. The goal of our study was to assess a relationship between serum IL-6 and cortisol in acute ischemic stroke. Twenty two patients with ischemic stroke and 17 controls were included. Serum samples were collected on the 2nd day of stroke at 6:00, 10:00 18:00, 22:00 h and at the same time points in control group. Cytokines and cortisol levels were measured using ELISA method. Serum IL-6 and cortisol levels were higher in stroke patients than in controls. Cortisol displayed diurnal variations in both stroke patients and controls. In contrast with control subjects, serum IL-6 levels did not display diurnal variations in stroke patients. In stroke patients, but not in controls, IL-6 level correlated significantly with cortisol level and morning serum IL-6 level independently predicted evening/night cortisol level. In conclusion, brain ischemia could stimulate IL-6 release in blood and in this way modulate hypothalamo-pituitary-adrenal axis.