Inhibition of hemozoin-induced neuroinflammation by the antimalarial drug artesunate

Introduction
Cerebral malaria (CM) has been linked to CNS inflammation [1][2], partly due to Plasmodium metabolic by-product, hemozoin inducing neuroinflammation and neuronal damage [3]. This study evaluated effects of the antimalarial drug artesunate on the release of pro-inflammatory media-tors in BV-2 microglia activated with a synthetic hemozoin (sHZ).
Methods
BV-2 microglial cells were treated with artesunate (0.025, 0.05, 0.1 and 0.2μM) and stimulated with sHZ (400μg/ml) for 24 hours. Culture supernatants were analysed for production of nitric oxide (NO) using Griess assay (Promega). Levels of pro-inflammatory cytokines IL-1β, TNF-αandIL-6 in were evaluated with mouse ELISA kits (Invitrogen). Caspase-1 activity in live cells was determined with caspase-1 Glo®inflammasomeassay (Promega). Data were analysed using ANOVA (one-way analysis of variance) with Tukey's Post-hoc test (multiple comparisons).
Results
Stimulation of BV-2 cells with sHZ (400μg/ml) resulted in significant increase in levels of TNF-αin culture supernatants (p*** < 0.001), when compared to unstimulated cells. However, in the presence of 0.025, 0.05, 0.1, and 0.2μM of artesunate, TNF-αrelease was reduced by40%,58%,65% and76%, respectively when compared with sHZ stimulation alone (100%). Similarly, sHZ induced an increase in the release of IL-1βwhen compared to unstimulated cells. However, on pre-treating cells with 0.05, 0.1, and 0.2μM artesunate, IL-1βproduction was reduced by50%,68% and74% in comparison with sHZ stimulation alone. Furthermore, sHZ-induced increased production of IL-6 was significantly reduced in the presence of artesunate. Analysis of culture supernatants revealed that 24-hour stimulation of BV-2 microglia resulted in increased levels of nitric oxide (NO), when compared with unstimulated cells. On pre-treating the cells with 0.025, 0.05, 0.1, and 0.2μM of artesunate, nitrite production was reduced by72%,81%,85% and88%, respectively. Artesunate (0.025, 0.05,0.1,0.2μM) also produced significant(p** < 0.01) reduction in caspase-1 activity in sHZ-activated BV-2 microglia.
Conclusions
Results of this study suggest that reduction in hemozoin-induced inflammatory responses by artesunate may be a valuable pharmacological strategy in reducing inflammatory components of CM neuropathogenesis.