1467-P: Chemical Profiles of Acinar Tissue and Pancreatic Islets from Healthy and T2D-Affected Pancreata

Both the endocrine and exocrine pancreas demonstrate morphological and chemical changes associated with T2D development. Despite significant progress, chemical profiles of the islets and acinar tissue following disease progression are not well characterized. In this work we investigated isolated populations of pancreatic islets (n=18) and acinar tissues (n=7) collected from healthy and T2D affected pancreata using several mass spectrometry (MS) approaches. Samples are provided by the ADI IsletCore and the Network for Pancreatic Organ Donors with Diabetes (nPOD) . Both peptide and metabolite profiles were determined and compared via chemical profiling with matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance MS. Not surprisingly, the peptide profiles from T2D islets demonstrated lower signal intensities compared to healthy islets (ROC analysis, AUC=0.9) . Somatostatin, pancreatic icosapeptide, and insulin-related signals are most decreased. Preliminary data for acinar tissues indicate lower peptide levels in samples collected from T2D-affected (n=2) vs. healthy (n=5) pancreata. Several unique peptides are detected specifically in acinar tissue obtained from T2D-affected pancreata. Liquid chromatography-MS reveals a complex endogenous peptide complement of acinar tissue. Analysis of extracellular media for both islet types demonstrated similar differences (AUC=0.7) indicating higher levels of observed peptides in preparations from healthy islets, perhaps suggesting that peptides are released from the islets during shipment. Integrity of received islets was verified using dithizone staining prior to measurement. In contrast, almost no peptide markers of acinar tissue are found in corresponding extracellular media. Our results enhance knowledge on biochemical signature of T2D in the pancreas.