Association of stress-related limbic activity and baseline interleukin-6 plasma levels in healthy adults

Abstract There is a bidirectional interaction between peripheral inflammatory processes and the brain. In the context of stress, top-down effects on the immune system have already been studied, but bottom-up effects of peripheral inflammation on neural processes are still unclear. In the present study, baseline plasma levels of the cytokine interleukin (IL)-6 were obtained as a measure of peripheral inflammatory processes and psychosocial stress was induced in 78 healthy adults during functional magnetic resonance imaging. The association of IL-6 with stress-related neural activation in the amygdala, anterior insula, and anterior cingulate cortex as regions of interest was explored. In order to account for individual differences in the stress response, salivary cortisol increase was also considered in the analyses. Stress task-related neural activity in the amygdala and anterior insula was significantly and negatively associated with IL-6 levels only in participants showing a cortisol response. These results suggest that peripheral inflammatory processes might affect the evaluation of a social stressor and highlight that individual differences in stress task responses should be considered in future studies.