A joint Australian-Brazilian research project has for the first time identified the molecular mechanism behind the characteristic retinal lesions and tissue loss associated with toxoplasma parasite infections.
The study, which is the first use of laboratory methods to understand how these lesions form, might lead to more effective treatments for the condition.
An international research team, consisting of researchers from Flinders University and University of São Paulo, Brazil, examined how the toxoplasma parasite causes the distinctive lesion, which is often the most common clinical presentation of an infection.
After monitoring patients presenting with ocular toxoplasmosis to a Brazilian eye clinic, the team found over 90% of infected eyes featured the typical lesion.
The team found retinal pigment cells infected by the parasite secrete vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF)1, while also reducing production of thrombospondin (TSP)1. These changes in infected cells prompt neighbouring uninfected retinal cells to overgrow, making them more susceptible to infection and prompting the development of the condition’s typical lesions.
Professor Justine Smith, strategic professor in eye & vision health at Flinders University and co-investigator on the project, told Insight international collaboration was integral to the project’s success.
“We have a special setup with my team in Adelaide where we can do research using human eye cells and eye tissue. That’s quite unique; it’s not that easy to do the sort of work that we do in many other parts of the world,” Smith said.
“In Brazil, there is a very large population and they see a lot of patients with toxoplasmosis. That made sense in terms of the clinical side.
“I think that this concept of multinational collaboration, or bringing more than one place into a piece of research work, makes the research stronger because different areas of the world have different research strengths in different ways.”
Researchers speculated that future treatments might include manipulating these proteins. This would be a significant development for regions where the condition is endemic, such as Brazil.
“There is no cure for toxoplasmosis, which is most often food borne,” said Dr Joao Furtado, co-investigator on the project from University of São Paulo and the International Agency for Prevention of Blindness, said.
“The World Health Organisation recommends food safety measures that include hand-washing, use of clean water in food preparation, and proper cooking.”
Smith said the number of people in Australia that have toxoplasmosis is not clear, although several older studies looking at antibodies in blood suggest it could be as high as one third of the population.
The study was published in the journal Microorganisms.