Neuronal apoptosis, metallothionein expression and proinflammatory responses during cerebral malaria in mice

BackgroundCerebral malaria (CM) is an acute encephalopathy in humans due to the infection with Plasmodium falciparum. Neuro-cognitive impairment following CM occurs in about 10% of the treated survivors, while the precise pathophysiological mechanism remains unknown. Metallothionein I + II (MT-I + II) are increased during CNS pathology and disorders. As previously shown, MT-I + II are neuroprotective through anti-inflammatory, antioxidant and antiapoptotic functions. We have analyzed neuronal apoptosis and MT-I + II expression in brains of mice with experimental CM.MethodsC57BL/6j mice, infected with Plasmodium berghei ANKA, were studied on day 7, day 9, and when presenting signs of CM on days 10–12. We investigated brain histopathology by immunohistochemistry and TUNEL (Terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-digoxigenin nick end labeling). For statistics, we used quantitation (cellular counts) of the analyzed variables.ResultsDuring CM, we observed significant inflammatory responses of F4/80+ microglia/macrophages and GFAP+ reactive astrocytes and increased immunoreactivity of 8-oxoguanine (marker of oxidative stress). As novel findings, we show: (1) a localized CM-induced neuronal apoptosis (detected by TUNEL) indicating severe and irreversible pathology. (2) A significant increase in MT-I + II expression in reactive astrocytes, macrophages/microglia and vascular endothelium.InterpretationThis is the first report showing apoptosis of neurons in CM by TUNEL, pointing out a possible pathophysiological mechanism leading to persisting brain damage. The possible neuroprotective role of MT-I + II during CM deserves further attention.