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Following cardiac surgery, 20 to 30 per cent of patients develop Acute Kidney Injury (AKI); with patients receiving a blood transfusion during surgery at an increased risk of developing this complication.

While it has long been observed by clinicians, little was known about the cause of cardiac surgery-associated AKI.

After a joint clinical and experimental study, conducted in Melbourne, Australia and Nantes, France, the researchers discovered that patients who received higher amounts of the protein myeloid-related protein_14 (MRP_14) through transfusion are at higher risk of developing AKI.

Indeed, experimental data suggests that MRP_14 could lead to renal damage by inducing the accumulation of neutrophils – a type of immune cells that contribute to causing inflammation. While they usually protect against bacterial infection, neutrophils can also accidentally cause damage to healthy tissues.

In this study, the team found that during AKI, neutrophils damage the kidneys by trogocytosis, a process where a cell rips the outer membrane from other cells and has been likened to “cannibalism”.

In the study published in JACC: Basic to Translational Science, the researchers concluded that monitoring the levels of MRP14 in blood before transfusion, or reducing its amount or activity, may prevent cardiac surgery-associated AKI.

“These findings take us several steps closer to understanding and treating cardiac surgery-associated AKI,” explains Professor Antoine Roquilly from Nantes University and CHU Nantes.

“Based on these results, Dr. Vourc’h, the first author of this work, is now developing new research projects to demonstrate that new blood transfusion strategies can enhance patient outcomes,” Professor Roquilly adds.

This collaborative work also demonstrates the strength of the year-long collaboration between the University of Melbourne and Nantes University in translational immunology.

University of Melbourne Professor Jose Villadangos, immunologist and cell biologist at the Doherty Institute and the Bio21 Institute, credits the collaboration between surgeons and scientists for unlocking this new knowledge.

“It was quite serendipitous really, but we were able to bring together clinicians working in ICU with basic researchers, and together work on something that may lead to improve the life of many,” says Professor Villadangos.

"The links we have established will continue in the future and, we anticipate, deliver more positive outcomes. This illustrates the importance of nurturing multidisciplinary research among local institutions and across national borders,” adds Professor Villadangos.

This work was done in collaboration with researchers from the Doherty Institute, University of Melbourne, Nantes University, CHU Nantes and Etablissement Français du Sang (EFS).

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Funding: Agence Nationale de Sécurité du Médicaments, National Health and Medical Research Council (NHMRC) of Australia, School of Biomedical Sciences-Department of Surgery at the University of Melbourne
DOI: https://doi.org/10.1016/j.jacbts.2022.02.019