Biophysical analysis of astrocytes apoptosis triggered by larval E/S antigen from cerebral toxocarosis-causing pathogen Toxocara canis.

Toxocarosis is a zoonosis caused by the transmission of the Toxocara canis (T. canis) larvae to humans. Its infectious third-stage larvae can invade the brains of paratenic hosts. The resultant brain damage can result in cerebral toxocarosis (CT). Astrocytes have important neurotrophic and neuroprotective functions in the brain. Substantial studies have shown that astrocyte apoptosis may contribute to the pathogenesis of many acute and chronic neurodegenerative disorders. We propose an alternation detection method, a combination of the astigmatic detection microscopy (ADM) and atomic force microscopy (AFM) techniques, to investigate the apoptosis of astrocytes triggered with T. canis larval excretory/secretory (Tc E/S) antigen. The variation in the pathology of a cell's morphological changes was investigated with ADM and AFM analyses and then confirmed by western blotting. The results showed that the round cells increased as the concentration of Tc E/S antigen and incubated time increased. In addition, the mean height of apoptotic cells was approximately twice that of untreated normal cells, which meant there was correlation between the Tc E/S antigen treatment and cell height. For each cleaved caspase-3 in the cells cocultured with Tc E/S antigen and incubated for 9 h, the corresponding intensities increased about 34-fold (34.4 ± 1.8) compared with those of the control cells. This method can provide researchers with a perspective for understanding the limited information on the mechanism of astroglial injury and death during a T. canis larval invasion in a brain infection.