BACKGROUND/ PURPOSE: Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects. Taking into account the opposing needs of limiting parasite multiplication and minimizing tissue destruction, the infection imbalance most often involves CD4 and CD8 T lymphocytes that play the lead role in adaptive immunity to T. gondii. The aims of our study were to develop murine models of toxoplasmosis and to study the immune responses to the infection. METHODS: Two murine models were studied: (i) intravitreal injection of T. gondii (primary infection) and (ii) intraperitoneal inoculation at birth and reinfection by intravitreal injection. Clinical and histological data were determined. mRNA-cytokine levels were measured in ocular samples obtained from mice with toxoplasma chorioretinitis using RT-PCR. RESULTS: Intravitreal injection of T. gondii led to chorioretinitis. Primary infection was characterized by severe chorioretinitis when compared with reinfection. mRNA levels of IFN-gamma, TNF-alpha, and iNOS were increased in infected mice. DISCUSSION: TH1 cells may mitigate chorioretinitis by limiting T. gondii proliferation. Further studies are needed to explore ocular immune regulation. These primary results may open new in vivo therapeutic approaches.
BACKGROUND/ PURPOSE:Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects. Taking into account the opposing needs of limiting parasite multiplication and minimizing tissue destruction, the infection imbalance most often involves CD4 and CD8 T lymphocytes that play the lead role in adaptive immunity to T. gondii. The aims of our study were to develop murine models of toxoplasmosis and to study the immune responses to the infection. METHODS: Two murine models were studied: (i) intravitreal injection of T. gondii (primary infection) and (ii) intraperitoneal inoculation at birth and reinfection by intravitreal injection. Clinical and histological data were determined. mRNA-cytokine levels were measured in ocular samples obtained from mice with toxoplasma chorioretinitis using RT-PCR. RESULTS: Intravitreal injection of T. gondii led to chorioretinitis. Primary infection was characterized by severe chorioretinitis when compared with reinfection. mRNA levels of IFN-gamma, TNF-alpha, and iNOS were increased in infected mice. DISCUSSION: TH1 cells may mitigate chorioretinitis by limiting T. gondii proliferation. Further studies are needed to explore ocular immune regulation. These primary results may open new in vivo therapeutic approaches.