Clofazimine against cerebral toxoplasmosis in diabetic and dexamethasone-immunosuppressed mice: ultrastructural and semiquantitative transmission electron microscopic study

Abstract

Cerebral toxoplasmosis is a common opportunistic parasitic infection of the CNS caused by the Toxoplasma gondii parasite. Host immunosuppression can affect disease outcomes. To explore the changes in the cerebral cortical ultrastructure accompanying the infection in different immune-altered models and to find an effective treatment against the infection, we tested the possible therapeutic effect of clofazimine (CFZ) (the FDA-approved antimycobacterial drug) against the infection using 60 male CD1 Swiss Albino mice divided into 6 groups: 3 dexamethasone (DEX)- treated groups (DEX-only, DEX-infected, and DEX-infected-treated), and 3 streptozotocin (STZ)-induced type 1 diabetic groups (STZ-only, STZ-infected, STZ-infected-treated). The worst ultrastructural changes were observed in the diabetic and diabetic-infected groups, characterized by a significant increase in neuronal apoptotic and necrotic nuclei (P < 0.05) and changes in the numbers and structure of glial cells compared to the DEX and DEX-infected groups. CFZ (at a dose of 10 mg/kg/day for 3 days starting on 45th day post infection) significantly improved cortical neuronal ultrastructural changes in both models (P < 0.05), reduced microglial numbers, increased astrocyte numbers, and restored brain capillary integrity and axonal growth, in addition to significantly reducing mature cyst numbers in both models (P < 0.05). However, the drug didn't reduce the number of atrophic and necrotic cysts in the infected-treated groups. So, in our study, CFZ showed preclinical promise in treating experimental cerebral toxoplasmosis and reducing the parasitic cyst burden, highlighting the adverse impact of the host's altered immune status on brain tissue and the course of the infection, especially in diabetes.