The in vitro immunosuppressive effects of moclobemide in healthy volunteers

Background: Many studies have demonstrated that major depression is related to an activation of the inflammatory response system (IRS) with an increased production of proinflammatory cytokines. It has been shown that tricyclic antidepressants and serotonin reuptake inhibitors suppress the activation of the IRS in depression and have negative immunoregulatory effects in vitro. Little is known on the immune effects of moclobemide, a reversible monoamine oxidase A inhibitor. Methods: We examined, in nine normal volunteers, the in vitro effects of moclobemide on the production of interleukin-6 (IL-6), IL-8, tumor necrosis factor-α (TNFα), interferon-γ (IFNγ), IL-10 and the IL-1 receptor antagonist (IL-1RA) by diluted whole blood stimulated or not with lipopolysaccharide (LPS)+phytohemagglutinin (PHA). Results: Moclobemide 10−3 and 10−5 M significantly suppressed the unstimulated production of TNFα and IL-8, and significantly enhanced the stimulated-production of IL-10. The production of IL-6, IL-1RA and IFNγ was not significantly affected either in the unstimulated or stimulated conditions. Conclusions: Moclobemide has negative immunoregulatory capacities through inhibition of the production of proinflammatory cytokines, i.e. TNFα and IL-8, and through enhancement of the production of IL-10, an anti-inflammatory cytokine.