Transcriptomic profile in pancreas biopsies for monitoring graft rejection
Pedro Ventura Aguiar1,2, Maria Jose Ramirez-Bajo2, Laura Sanchez Salom2, Candice Roufosse3, Miriam Cuatrecasas4, Jordi Rovira2, Elisenda Bañón-Maneus2, Constantino Fondevila5, Josep M. Campistol1,2, Pablo Uva6, Cinthia Drachenberg7, Fritz Diekmann1,2.
1Renal Transplant Unit, Hospital Clínic Barcelona, Barcelona, Spain; 2Laboratori Experimental de Nefrologia i Trasplantament , Fundacio Clinic - IDIBAPS, Barcelona, Spain; 3Department of Immunology and Inflammation, Centre for Inflammatory Diseases, Faculty of Medicine, Imperial College, London, United Kingdom; 4Department of Pathology, Center of Biomedical Diagnosis (CDB), Hospital Clínic Barcelona, Barcelona, Spain; 5Hepato-Bilio-Pancreatic Surgery and Digestive Transplant Unit, Hospital Clínic Barcelona, Barcelona, Spain; 6Kidney Pancreas Transplantation, Instituto de Trasplantes y Alta Complejidad (ITAC - Nephrology), Buenos Aires, Argentina; 7Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, United States
Introduction: Overall, almost 30% of pancreas transplant recipients present an episode of rejection during the first year after transplantation. Pancreas biopsy is the gold standard for the diagnosis and treatment pancreas rejection since other modes of monitoring pancreas rejection are neither sensitive nor specific enough. Immune infiltrates of graft from transplantations are usually evaluated with immunohistochemistry, immunofluorescence and flow cytometry. Interestingly enough, Banff schema has refined the diagnosis in kidney antibody-mediated rejection (ABMR) 4 times in the last 10 years, whereas in pancreas transplantation it has remained unchanged since its first description in 2011.
Identification of genetic variants to aid in individualized treatment of solid organ allograft recipients would be associated with outcomes and personalized medicine. In kidney, liver, and heart transplantation, the molecular microscope has been paving the way towards the introduction of these novel transcriptomic fingerprints into the clinical practice and provide assistance into decision making. In pancreas transplantation only one work explored the correlation between the transcriptomic fingerprint and development of de novo ABMR using a 34 gene-set.
Methods: We are developing a retrospective multicentre observational study aiming at comparing the transcriptomic profile of RNA obtained from paraffin embedded pancreas graft biopsies, and compare to the clinical and biochemical markers, and histological diagnosis. Study is being developed using pancreas graft biopsies performed previously per protocol or clinical indication. Samples from a range of different histological diagnosis (according to the Banff criteria) will be included (estimated n=20/diagnosis). Briefly, 3 sections of 20-micron thickness were obtained from FFPE blocks and RNA extraction were performed with the RNeasy FFPE Kit (Qiagen). Quality and quantity of RNA was checked by NanoDrop ND1000 (Thermo Scientific) spectrophotometer.
For transcriptome analysis we are applying the Human Organ Transplant panel from Nanostring©, which includes a comprehensively profile of 770 genes across 37 pathways to identify biomarkers for rejection, uncover the mechanisms of tissue damage, and study toxicities brought on by immunosuppressive drugs.
We expect to have preliminary results by May and some more conclusive data by November 2021.