Apoptosis within mouse eye induced by Toxoplasma gondii

Area of Science:

• Ophthalmology
• Immunology
• Parasitology

Background:

• Ocular toxoplasmosis, caused by Toxoplasma gondii, is a significant cause of infectious blindness worldwide.
• Understanding the host-pathogen interactions in the eye is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the induction and patterns of apoptosis in the eyes of C57BL/6 mice following Toxoplasma gondii infection.
• To determine if apoptosis plays a role in the host's immune response to ocular Toxoplasma gondii.

Main Methods:

• Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) technique.
• C57BL/6 mice eyes were inoculated intraocularly with 50 or 500 tachyzoites of T. gondii.
• Ocular tissues were analyzed at various time points post-infection for pathological changes and apoptotic cells.

Main Results:

• Apoptosis of inflammatory cells and keratocytes was observed in the anterior chamber and cornea, particularly at higher parasite doses (500 tachyzoites).
• Apoptotic inflammatory cells increased in the anterior chamber and vitreous humor.
• Apoptotic retinal cells were detected in the inner retina 4 days post-infection with higher parasite loads.

Conclusions:

• Toxoplasma gondii infection induces significant apoptosis in ocular tissues, including inflammatory cells, corneal cells, and retinal cells.
• The apoptosis of infiltrated inflammatory cells suggests a potential host-mediated mechanism for controlling parasite load within the infected eye.
• These findings contribute to understanding the immunopathology of ocular toxoplasmosis.