NIH Initiative to Improve Understanding of the Pancreas, Islet, and Autoimmunity in Type 1 Diabetes: The Human Pancreas Analysis Program (HPAP)

Abstract

Type 1 diabetes risk can reliably be predicted by markers of autoimmunity, but approaches to prevent or modify the underlying disease process are needed. We posit this void fundamentally results from a limited understanding of immune-islet cell interactions within the pancreas and relevant immune organs, contributions of β-cells to their own demise, and epigenetic predispositions affecting both immune and islet cells. Because biopsy of the human pancreas and pancreatic lymph nodes carries risk and the pancreas begins to autodigest soon after death, detailed cellular and molecular phenotyping of the human type 1 diabetes pancreas is lacking, limiting our understanding of the mechanisms of β-cell loss. To address these challenges, the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases established the Human Pancreas Analysis Program (HPAP) to procure human type 1 diabetes pancreata for an extensive array of tissue-based, cellular, and epigenetic assays aimed at critical knowledge gaps in our understanding of the local immune attack and loss of β-cells. In this Methodology Review, we describe how HPAP is performing detailed islet and immune cell phenotyping and creating publicly available data sets with the goals of an improved understanding of type 1 diabetes and the development of more effective treatments to prevent or reverse the disease.

Figure 1

HPAP workflow. HPAP, working with nPOD, identifies organ donors of interest (recent-onset type 1 diabetes, antibody-positive donors, and control subjects). For organ donors <30 years old without diabetes, the OPO, using HPAP/nPOD protocols and reagents, screens for presence of GADAs. If a suitable organ donor is identified, pancreas and immune tissues are shipped to UPenn for processing. The tissue and islets are then analyzed at Vanderbilt University and UPenn. All data are coregistered and integrated in a publicly accessible database (PANC-DB) (https://hpap.pmacs.upenn.edu). Ab, antibody.

Figure 2

IMC of the human pancreas developed by HPAP. Pancreatic tissue sections are staining with 33 antibodies conjugated to heavy metal isotopes. The washed slide is then subjected to laser ablation, and the amount of each isotope per tissue voxel is recorded. The data can be used for image reconstruction or for quantitative analysis of marker protein expression in each cell in the section. Reprinted with permission from Wang et al. (32).

Figure 3

Examples of islet assays performed by HPAP. A: Patch clamp electrophysiology recording of a pancreatic β-cell. The top trace shows firing in the absence and the bottom trace (red) in the presence of 15 mmol/L glucose. Note the increased rate of depolarization from 100 to 150 s during the incubation with glucose. B: Oxygen consumption rate (OCR) of human islets. Note the large stimulation by 16.7 mmol/L glucose (G). C: Flow mass cytometry for the precise quantification of islet composition. Top, general principle. Bottom, tSNE plots of islet cell clusters with α-cells (glucagon [GCG]) and δ-cells (somatostatin [SST]) indicated. Pie chart from the HPAP website illustrating endocrine cell proportions.