Oral contraceptives modulate the anti-inflammatory activity of Acanthamoeba-stimulated human macrophage

PURPOSE. Macrophages are effector cells of the non-specific immune response involved in the first recognition and response to pathogens. Sex hormones may play an important role in regulating the immune responses and macrophages possess functional sex hormone receptors. Therefore, the aim of this study was to evaluate whether the use of oral contraceptives (OCs) can affect macrophage activity against Acanthamoeba. To this end, we evaluate the effect of OCs on pro-inflammatory and anti-inflammatory cytokines release by human macrophages in response to Acanthamoeba-derived cell-free conditioned medium (aCM) and to known agonists of TLR4 and TLR2 receptors (used as positive controls). METHODS. Primary human peripheral blood monocytes from healthy adult women treated (FOCs) or non-treated (Fs) with OCs were isolated during the follicular phase of their menstrual cycle. Human monocyte-derived macrophages (MDMs) were obtained from each sub-population, and stimulated with either aCM, LPS or Pam2CSK4, in vitro. Release of TNF-α, IL-6, IL-10 and IL-8 was investigated at specific hours post-stimulation, by Enzyme Linked Immuno Sorbent Assay (ELISA). All experiments were performed in triplicate. Statistical difference was evaluated with the two-tailed Student t test and two-way analysis of variance (ANOVA), followed by Bonferroni post test, using Graph-Pad Prism (GraphPad Software Inc.). RESULTS. Our data showed that by F-MDMs aCM induced a significant release of IL-6 and IL-10 throughout the time course; and IL-8 production at 18h post-stimulation. Of interest, a highly significant reduction of IL-8 and IL-10 was detected in FOC-MDMs in comparison with F-MDMs. DISCUSSION. At the moment it is difficult to explain the impact that the reduced production of IL-8 and IL-10 observed in FOC-MDMs aCM-stimulated might have in Acanthamoeba infections. We hypothesize that the reduction of a already poor production of IL-8 might reduce macrophage ability to recruit neutrophils and other granulocytes in the site of infection, to the benefit of Acanthamoeba. On the other hand the reduction of IL-10 might promote the inflammatory response and the macrophage antimicrobial activity, to the detriment of the protozoan. CONCLUSIONS. The use of OCs might influence the immune-modulatory activity of macrophages during Acanthamoeba infections.