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Apoptotic exosomes as drivers of renal inflammation and dysfunction

Marie-Josée Hébert
Centre Hospitalier de l'Université de Montréal
Kidney Health Research Grant
2022 - 2024
$100,000
Predictive Biomarkers, Transplantation, Renal Failure

Lay Abstract

The kidneys are vital organs in that they clean the blood and dispose of waste produced by all the cells of the body. About 20% of the blood pumped by the heart is filtered by kidneys at a given time. This translates into 180 liters a day on average that are purified by the kidneys. To do so, an abundant network of large and small vessels are present within kidneys. These blood vessels allow filtration of a large quantity of blood and excretion of waste into the urine. In previous work, our team showed that damage to the tiniest kidney blood vessels, called peritubular capillaries, is one of the most important cause of renal failure. This is especially true in patients who have received a kidney transplant. In these patients, damage to these small blood vessels at the time of transplantation is associated with reduced survival of the transplanted kidney. This means that damage to small blood vessels will cause kidney grafts to stop working prematurely and that transplanted patients will have to go back on dialysis or receive a second kidney transplant. We also found that some antibodies can damage these small blood vessels at the time of kidney transplantation. Antibodies help us fight infections but also help dispose of dead cells in organs that have been damaged. These ‘’disposal antibodies’’, especially one that is called anti-LG3, can damage those very precious tiny vessels. In turn, damaged vessels will release small pieces of cells we call ‘’apoptotic exosome-like vesicles’’. These pieces of cells activate the immune system to produce more harmful antibodies. This vicious cycle that can destroy permanently small blood vessels and cause renal failure. Our group was the first to characterize anti-LG3 antibodies and also the small pieces of cells that are released by injured blood vessels. We discovered that when kidneys enter this vicious cycle of injury, attraction of harmful antibodies and further injury, they also attract white blood cells that move into the kidneys to produce locally harmful antibodies. Here, we will study how to prevent these antibodies from damaging kidneys but also how to prevent kidneys and the immune system in general to produce antibodies harmful to small kidney vessels, with the hope of making kidney transplants work better and longer.