Neuroimmunomodulation in Depression: A Review of Inflammatory Cytokines Involved in this Process

Depression is a debilitating mental disease that affects a large number of people globally; however the pathophysiological mechanisms of this disease remain incompletely understood. Some studies have shown that depression is associated with inflammatory activity, and the mode of action of several antidepressants appears to involve immunomodulation. In this case, the induction of a pro-inflammatory state in healthy or depressive subjects induces a ‘sickness behaviour’ resembling depressive symptomatology. Potential mechanisms of pro-inflammatory cytokines are effects on monoamine levels, disruption of the hypothalamic–pituitary–adrenal axis, activation of the pathological microglial cells, such as the macrophages and alterations in neuroplasticity and brain functions. Thus, this review will highlight the role of inflammation in depression, the possible mechanisms involved, and also explore effective treatments that act on the immune system.