Kidney transplants are highly effective in treating issues like kidney failure or malfunction. However, because a transplant involves the introduction of an entirely foreign organ into one's body, many kidney transplants are rejected by the body into which they are put. Often, the person becomes ill and may die unless another transplant is performed. Sometimes, doctors will put patients on medicines to suppress their immunity so that their bodies no longer reject the transplant, but this can cause more harm than good if misused, as the patients will be susceptible to infection.

However, all of this could potentially be avoided in the future.

A new research effort has found a way to look for three biomarkers in a transplant patient's urine to predict wither the transplant will soon be rejected. "The development of a noninvasive test to monitor kidney transplant rejection status is an important advance that will allow doctors to intervene early to prevent rejection and the kidney injury it causes, which should improve long-term outcomes for transplant recipients," said Anthony S. Fauci, M.D., director of National Institute of Allergy and Infectious Diseases (NIAID) who sponsored this research. Before this method, doctors would take biopsies of newly transplanted kidneys to check for rejection-related damage before they knew what could be done to help a patient whose transplant was going awry. However, this method takes a lot of time, is invasive, and can lead to further complications.

The study consisted of 485 kidney transplant recipients. Urine samples were collected four times a month for a year after they received their transplant. Researchers looked for three specific biomarkers to indicate whether the kidney was in danger of being rejected by the person's immune system. These biomarkers were mainly genetic signatures of the immune cells that would act against the kidney. The genetic signature is essentially a byproduct and is eliminated in the urine; this is useful for the researchers, as they do not have to go into a person's body, just analyze what comes out of it.

Two-hundred-and-twenty of the studied patients underwent a biopsy and their urine samples were matched to potential damage found in the biopsy. Researchers were able to match the existence of the biomarkers in urine with patients whose bodies were rejecting their transplants. Of 163 patients who received biopsies due to suspected rejection, all of the patients had high levels of all three biomarkers for transplant rejection in their urine. Similarly, the level of biomarkers present in the urine increased as the rejection worsened.

The presence of the biomarkers at elevated levels in patients suspected of having transplant rejection is promising. The biomarker elevation is also a slow process, so medical professionals can use this to their advantage to look for warning signs as well as predict whether the transplant with be rejected before symptoms arise in patients. The researchers found a characteristic sharp rise in the biomarkers as many as 20 days before a biopsy confirmed rejection. Similarly, the biomarker values remained relatively constant and under the threshold for rejection for patients who did not show any signs of transplant rejection. These findings suggest that it can be possible to treat future rejection before substantial kidney damage occurs.

"The test described in this study may lead to better, more personalized care for kidney transplant recipients by reducing the need for biopsies and enabling physicians to tailor immunosuppressive therapy to individual patients," said Chief Nancy Bridges, M.D., NIAID transplantation branch chief and co-author of the paper.

Source: Suthanthiran M, Schwartz JE, Ding R, et al. Urinary-Cell mRNA Profile and Acute Cellular Rejection in Kidney Allografts. New England Journal of Medicine. 2013.