Modulation of IFN-γ, TNF-α, IL-10 and IL-12 production by artesunate in mitogen treated splenocytes

This study compared the effects of artesunate and chloroquine on mitogen-induced splenocyte release of several important cytokines involved in the pathogenesis of malaria. Concanavalin A (Con A) or Lipopolysaccharide (LPS) was used to stimulate splenocytes from healthy C57BL/6 mice in an in vitro system. Splenocytes were stimulated for 24 or 48 h at 37°C and in 5% C02 in the presence or absence, respectively, of different concentrations of chloroquine and artesunate. Culture supernatants were tested for TNF-α (after 24 h stimulation), IFN-γ (after 48 h stimulation), IL-10 (after 24 h stimulation) and IL-12p40 (after 48 h stimulation), using ELISA. Chloroquine, but not artesunate, inhibited ConA-induced IFN-γ release over the drug concentration range of 3-30 μM. Artesunate inhibited ConA IFN-y release at the concentration of 90 μM, compared with controls (p = 0.0138). Over the dose range 3-30 μM, artesunate stimulated production of IL-12p40, while chloroquine caused dose-dependent inhibition (p = 0.03). Both chloroquine and artesunate produced dose-dependent inhibition of TNF-α, chloroquine being the stronger inhibitor over the same dose range. Artesunate had no effect on IL-10 production at the concentration of 3 μM but at the highest test concentration of 90 μM, artesunate almost eliminated the response. The differences in immunomodulatory activity observed between chloroquine and artesunate might explain the differences in therapeutic response in malaria and possibly the recrudescence associated with artesunate but not with chloroquine monotherapy. Further studies are necessary to understand better the role of the different immunological effects of antimalarial drugs on malaria treatment outcomes.