Interleukin-1 beta: a putative mediator of HPA axis hyperactivity in major depression?

There is extensive evidence that major depression, and particularly melancholia, is characterized by hypothalamic-pituitary-adrenal (HPA) axis hyperactivity as well as systemic immune activation, which may be accompanied by increased interleukin-1 beta production. Interleukin-1 beta is known to enhance HPA axis activity during an immune response. This study investigated whether interleukin-1 beta production is related to HPA axis activity in depressed subjects.The subjects were 28 inpatients with major or minor depression and 10 normal comparison subjects. The authors measured 1) the subjects' cortisol levels after an overnight 1-mg dexamethasone suppression test (DST) and 2) mitogen-stimulated supernatant interleukin-1 beta production by peripheral blood mononuclear cells.Statistically significant positive correlations between interleukin-1 beta production and post-DST cortisol values were found in the study group as a whole and in the depressed and normal subgroups separately.It is suggested that constituents of the immune response (such as interleukin-1 beta) in major depression may contribute to HPA axis hyperfunction in that illness.