Serum anti-inflammatory markers in general population subjects with elevated depressive symptoms

Anti-inflammatory substances have previously been suggested to show compensatory elevations in depressed individuals with pronounced inflammatory changes. In order to further clarify these observations, we examined depression-related alterations in the serum levels of anti-inflammatory markers interleukin (IL)-1 receptor antagonist (RA) and IL-10 and the pro-inflammatory marker IL-6 in 416 general population participants. Depression was evaluated with the Beck Depression Inventory (BDI). Participants with elevated depressive symptoms (BDI>14, n=44) had increased levels of IL-1 RA and IL-6. No changes were observed in their IL-10 levels. In multivariate modeling with adjustments for age, gender, obesity, regular smoking, alcohol use, metabolic syndrome, physical exercise, sleep disturbance, and the use of non-steroidal anti-inflammatory drugs, a high level of IL-1 RA was associated with an increased likelihood of belonging to the group with elevated depressive symptoms (OR for each 1 SD increase in the serum level of IL-1 RA: 2.17, 95% CI 1.35-3.48, p=0.001). The significance of IL-6 alterations did not persist in the same model. The pronounced secretion of anti-inflammatory marker IL-1 RA may reflect the presence of compensatory mechanisms during a depression-related inflammatory state.