A urine test could help diagnose graft dysfunction in kidney transplants

Researchers from Vall d'Hebron Barcelona Hospital Campus have led a study that opens the door to develop a simple urine test to determine the cause of kidney dysfunction in transplant patients. The work has followed 30 cases, in which samples of urine have been analysed to discover proteins with which it can be diagnosed if the organ problem has provoked a cell rejection or an infection by BK virus. It has been led by professionals from the Vall d'Hebron University Hospital, Dr. Òscar Len, Dr. Joan Gavaldà and Dr. Ibai Los Arcos of the Infectious Diseases group of Vall d'Hebron Research Institute (VHIR), and Dr. Francesc Canals, from the Proteomics group of the Vall d'Hebron Institute of Oncology (VHIO), with the collaboration of the Vall d'Hebron Renal Transplant Unit, led by Dr. Francesc Moreso. They have also participated the service of Nephrology of the Fundació Puigvert, the Hospital del Mar and the Bellvitge University Hospital. The research has been considered one of the most relevant studies of the 27th Congress of Clinical Microbiology and Infectious Diseases (ECCMID) and was presented at the conference press of the congress, and also received the award for best communication in the XXI Congress of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC).

In 25% of cases, the kidney transplant fails before age 5. Patients receiving a renal transplant require immunosuppressive treatment to prevent organ rejection. Insufficient medication can cause rejection of the organ by the patient's immune system and an excess can weaken the body's defences and open the door to a BK virus infection, which is acquired in infancy and is latent in the body. In this type of patient can be reactivated and cause renal graft dysfunction. The correct diagnosis of the two pathologies is fundamental because the treatment of these diseases is opposite. In the case of rejection, it is necessary to increase immunosuppression and decrease it in BK virus infection. Currently, to diagnose what causes graft dysfunction, it is necessary to perform a renal biopsy, a procedure that carries a certain risk, such as haemorrhagic complications.

A non-invasive test

Researchers have focused on designing a non-invasive method to distinguish whether kidney dysfunction is caused by rejection of the patient's body or the responsible of BK virus infection. As Dr. Ibai Los-Arcos explains, a member of the VHIR Infectious Diseases group with a Rio Hortega contract, "our first intention is to help differentiate patients who have acute rejection of BK virus nephropathy with a non-invasive method, though the detection of certain proteins in the urine, since the treatment for the two cases is totally opposite."

During the study, researchers have analysed urine samples from 30 patients. 10 had been diagnosed with rejection of the transplanted organ and another 10 with BK virus nephropathy. We also included 10 kidney transplant recipients without graft dysfunction as a control group. Of about 2000 human proteins detected, 10 differentiated patients with BK virus nephropathy from those who suffered rejection, and from controls.

The work of Vall d'Hebron Campus researchers may allow the development of a simple and inexpensive non-invasive test that would expand the range of diagnostic tools for kidney transplant specialists.