Future of non-invasive graft evaluation: A systematic review of proteomics in kidney transplantation.

Background: Despite the developments in the field of kidney transplantation, the already existing diagnostic techniques for patient monitoring are considered insufficient. Protein biomarkers that can be derived from modern approaches of proteomic analysis of liquid biopsies (serum, urine) represent a promising innovation in the monitoring of kidney transplant recipients.

Aim: To investigate the diagnostic utility of protein biomarkers derived from proteomics approaches in renal allograft assessment.

Methods: A systematic review was conducted in accordance with PRISMA guidelines, based on research results from the PubMed and Scopus databases. The primary focus was on evaluating the role of biomarkers in the non-invasive diagnosis of transplant-related complications. Eligibility criteria included protein biomarkers and urine and blood samples, while exclusion criteria were language other than English and the use of low resolution and sensitivity methods. The selected research articles, were categorized based on the biological sample, condition and methodology and the significantly and reproducibly differentiated proteins were manually selected and extracted. Functional and network analysis of the selected proteins was performed.

Results: In 17 included studies, 58 proteins were studied, with the cytokine CXCL10 being the most investigated. Biological pathways related to immune response and fibrosis have shown to be enriched. Applications of biomarkers for the assessment of renal damage as well as the prediction of short-term and long-term function of the graft were reported. Overall, all studies have shown satisfactory diagnostic accuracy of proteins alone or in combination with conventional methods, as far as renal graft assessment is concerned.

Conclusion: Our review suggests that protein biomarkers, evaluated in specific biological fluids, can make a significant contribution to the timely, valid and non-invasive assessment of kidney graft.