When a tumor develops, it creates a structure around itself called the tumor stroma, within which blood and lymphatic vessels ensure nutritional and respiratory biological exchanges. Lymphangiogenesis, i.e. the development of lymphatic vessels, is generally associated with a poor prognosis, as it favours the spread of metastases to other organs. By studying the cells that make up the wall of lymphatic vessels, a team from the University of Geneva (UNIGE) has made an unexpected discovery: an enzyme they express appears to play a key role in supporting immune cells, particularly when they are activated by anti-tumor treatments. These results, published in Nature Communications, could pave the way for improving the effectiveness of immunotherapies.
Blocking lymphangiogenesis to limit the risk of metastasis? The idea seemed promising but turned out to be disappointing.
”While it is true that lymphatic vessels promote metastasis, they are also essential for transporting immune cells and activating the anti-tumor immune response,” explains StĂ©phanie Hugues, a full professor in the Department of Pathology and Immunology and at the Geneva Centre for Inflammation Research in UNIGE Faculty of Medicine, who led this research. ”Their role is therefore more complex than we imagined, which is why we wanted to understand how the cells that make them up respond to the tumor microenvironment in order to influence the immune response.”
An enzyme that blocks the tumor’s defenses
The research team measured the gene expression of lymphatic endothelial cells, the cells that make up the wall of lymphatic vessels, in melanoma