C3 fixed in vivo to cornea from horses inoculated with Leptospira interrogans.

This research paper investigates why horses with leptospirosis, a bacterial disease, often suffer from recurrent uveitis, a type of eye inflammation. The researchers found that a protein called C3 attaches to the cornea of horses infected with Leptospira interrogans, and this, along with immune cells infiltrating the cornea, may be the cause of eye tissue damage.

Background and Aim

• The study focuses on leptospirosis, a bacterial disease that is often seen in horses. One of the recurrent symptoms of this disease is uveitis, an inflammation of the uvea or the middle layer of the eye.
• The researchers became interested in the role of the protein C3, which plays a significant role in the immune response. Specifically, they wanted to understand if C3 contributes to the tissue damage seen in recurrent uveitis associated with leptospirosis.

Methods and Findings

• The team inoculated horses with killed Leptospira interrogans bacteria and observed that C3 became bound to the cornea, particularly in areas that had become opaque.
• They carried out further tests in the lab using epithelial corneal cells which had been isolated from a tissue culture. After incubation with fresh horse anti-Leptospira serum, the researchers observed that C3 attached to the surface of the intact cells.
• Additionally, they noted an infiltration of neutrophils and lymphocytes, two types of white blood cells, into the cornea.

Conclusions

• This visible attachment of C3 proteins and the infiltration of immune cells possibly explains the mechanism that leads to tissue damage in the cornea of horses with leptospirosis.
• The observation that C3 is fixed to the epithelial corneal cells in vitro (in a controlled lab setting) after incubation with horse anti-Leptospira serum strengthens the researchers’ theory. This research could therefore lead to more effective treatments for leptospirosis-related eye conditions in horses.