Insights into immunopathology and triggering of apoptosis in chronic cerebral toxoplasmosis using murine models

ABSTRACT

@#Background: toxoplasmosis is a cosmopolitan protozoan disease with a wide range of neuropathology. Recent studies identified its potential association with several mental disorders e.g. schizophrenia dependable on apoptosis in their pathogenesis. We investigated value of toxoplasmosis to induce apoptosis of the neuronal cells. Methods: per-orally infected C57BL/6 mice with 15-20 cysts of the avirulent T. gondii Beverly strain at 9-11 weeks of age were examined 12 weeks later during parasite establishment. Distributions of the parasite’s cysts and the histopathological lesions in the brains were analyzed using Image J software. Relative expression of TNF-α and iNOS of cell-mediated immunity (CMI), Bax (pro-apoptosis) and Bcl-2 (anti-apoptosis) were all assessed using immunohistochemistry. Results: higher parasite burden was seen in the forebrain with p value < 0.05. Dramatically increased TNF-α, iNOS, and Bax expressions with Bax/Bcl-2 ratio 2.42:0.52 were reported (p value < 0.05). The significant correlation between Bax data and different CMI biomarkers including TNF-α and i-NOS was evaluated. Interestingly, no significant correlation was seen between TNF-α, iNOS, Bax and Bcl-2 expressions and location of the parasite. However, Bax/Bcl-2 ratio was statistically correlated with CMI biomarkers and whole sample mean parasite burden, p value < 0.05. Conclusion: Chronic toxoplasmosis exhibits an immense pro-apoptotic signal on the cerebral tissues of experimental mice.