Cytopathic changes in rat microglial cells induced by pathogenic Acanthamoeba culbertsoni: Morphology and cytokine release

To determine whether pathogenic Acanthamoeba culbertsoni trophozoites and l ysate can induce cytopathic changes in primary-culture microglial cells, mo rphological changes were observed by transmission electron microscopy (TEM) . In addition, the secretion of two kinds of cytokines, tumor necrosis fact or alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta), from microglial ce lls was observed. Trophozoites of pathogenic A. culbertsoni made contact wi th microglial cells and produced digipodia. TEM revealed that microglial ce lls cocultured with amoebic trophozoites underwent a necrotic process, acco mpanied by lysis of the cell membrane. TEM of microglial cells cocultured w ith amoebic lysate showed that the membranes of the small cytoplasmic vacuo les as well as the cell membrane were lysed. The amounts of TNF-alpha secre ted from microglial cells cocultured with A. culbertsoni trophozoites or ly sate increased at 6 h of incubation. The amounts of IL-1 beta secreted from microglial cells cocultured with A. culbertsoni trophozoites at 6 h of inc ubation was similar to those secreted from the control group, but the amoun ts decreased during cultivation with A. culbertsoni lysate. These results s uggest that pathogenic A. culbertsoni induces the cytopathic effects in pri mary-culture rat microglial cells, with the effects characterized by necros is of microglial cells and changes in levels of secretion of TNF-alpha and IL-1 beta from microglial cells.