BIOmarkers Before and After Kidney Transplantation

In clinical nephrology, the search for urinary, blood and tissue biomarkers of specific kidney diseases is an important goal. In recent years, the use of these biomarkers has made it possible to diagnose many renal diseases that affect the native kidney. In some cases, biomarkers may be useful in determining the evolutionary profile of the disease and thus the most appropriate therapeutic management.

The progression of these kidney diseases sometimes necessitates kidney transplantation for patients undergoing follow-up. Although the one-year survival rate for kidney transplantation has improved significantly over the last decade and is currently 90%, long-term survival is not increasing. Renal graft biopsy remains the reference method for the diagnosis and prognosis of various post-transplant conditions. This method has two limitations: i) it is an invasive procedure associated with complications, which means that it cannot be performed systematically on a large scale throughout the transplant process; ii) the sample size is limited and does not always allow a reliable prognosis to be made. The identification of urinary or blood biomarkers with diagnostic and prognostic value would allow an earlier diagnosis than that made by kidney biopsy. This would allow patients to be treated specifically and individually at an early stage, before damage to the kidney graft occurs, and would significantly improve long-term kidney graft survival.

The main objective of this study is to investigate blood, urine and tissue biomarkers in renal pathologies for diagnostic and prognostic purposes.

As this is an observational study, the main criteria of interest for analysis will include

• Exposure factors: blood and/or urine and/or tissue biomarkers
• Diagnostic criteria (presence or absence of the kidney disease of interest) and prognostic criteria (occurrence or absence of the event of interest).

Once the patient has been informed and has consented to participate in the study, and once the selection criteria have been verified:

1. Clinical data will be recorded in the medical record as part of routine care and then collected in the research database. Clinical data collected will include demographic, biological, clinical and imaging data.
2. The following samples will be collected at one time during the routine care examinations 17.5 mL of additional blood: 1 x 5 mL dry tube, 1 x 10 mL CPT tube and 1 x 2.5 mL PAXgen tube.
3. The excess of urine samples (50 to 100 mL) collected during the course of treatment is retained;
4. If kidney biopsies are performed as part of treatment, part of the sample will be diverted to the biological collection: 1 fragment, 5x5x5 mm.

For patients undergoing native renal biopsy:

A single blood and urine sample (17.5 ml blood: serum, PBMC, RNA) will be collected on the day of the renal biopsy.

In kidney transplant patients:

On the day of the kidney biopsy, patients will be admitted to the day hospital. An additional blood sample (17.5 ml blood: serum, PBMC, RNA) will be taken for each kidney biopsy performed as part of standard care. A urine sample (one to two 50 mL urine tube) is collected.

These blood, urine and tissue samples may be stored in a biological collection and used for constitutional genetic studies.