Hemozoin produced by Plasmodium falciparum during
malaria infection has been linked to the neurological dysfunction in
cerebral malaria. In this study, we determined whether a synthetic form of
hemozoin (sHZ) produces
neuroinflammation and neurotoxicity in cellular models. Incubation of BV-2 microglia with sHZ (200 and 400 µg/ml) induced significant elevation in the levels of TNFα,
IL-6, IL-1β, NO/iNOS, phospho-p65, accompanied by an increase in
DNA binding of NF-κB. Treatment of BV-2 microglia with sHZ increased
protein levels of NLRP3 with accompanying increase in caspase-1 activity. In the presence of NF-κB inhibitor
BAY11-7082 (10 µM), there was attenuation of sHZ-induced release of pro-inflammatory
cytokines, NO/iNOS. In addition, increase in
caspase-1/NLRP3
inflammasome activation was blocked by
BAY11-7082. Pre-treatment with
BAY11-7082 also reduced both phosphorylation and
DNA binding of the p65 sub-unit. The NLRP3 inhibitor
CRID3 (100 µM) did not prevent sHZ-induced release of TNFα and
IL-6. However, production of IL-1β, NO/iNOS as well as
caspase-1/NLRP3 activity was significantly reduced in the presence of
CRID3. Incubation of differentiated neural progenitor (ReNcell VM) cells with sHZ resulted in a reduction in cell viability, accompanied by significant generation of cellular ROS and increased activity of
caspase-6, while sHZ-induced neurotoxicity was prevented by
N-acetylcysteine and Z-VEID-FMK. Taken together, this study shows that the synthetic form of
hemozoin induces
neuroinflammation through the activation of NF-κB and NLRP3
inflammasome. It is also proposed that sHZ induces ROS- and caspase-6-mediated neurotoxicity. These results have thrown more light on the actions of malarial
hemozoin in the neurobiology of
cerebral malaria.