Proteomics has the ability to accurately characterize and quantitate proteins that are present during a particular disease state. Several studies have now been published describing proteomics advances in pancreatitis. In his August 2013 article, John A. Williams provides a review of proteomics work in pancreatitis, summarizes the experimental design, and suggests improvements for pancreatitis research.1
Animal models are commonly used in studying mechanisms of pancreatitis. Research by Yu et al. (2003) represents some of the earliest examples of studying protein changes.2 Their work employed AR42J cells as a model for rat acinar cells, and simulated pancreatitis by hyperstimulation with cerulein. Two-dimensional gel electrophoresis was utilized to separate proteins, and tryptic peptides were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This research of Yu et al. identified five upregulated proteins in pancreatitis-induced animals.
Another animal study involving cerulein-stimulated rats focused on the low molecular weight proteome. In their study, Lassout et al. (2010) employed strong homogenization followed by centrifugation to enrich the peptides.3 This time, proteins were identified using an LTQ Orbitrap (Thermo Scientific) mass spectrometer. Results of these experiments revealed 37 decreased proteins, 23 increased proteins and 17 increased proteins in the peptidome, based on the differential expression and on an experimental ratio greater than 1.50 or less than 0.66.
According to Williams, additional animal studies have also been completed. The combined results of those studies show a general trend of increased proteins related to stress, inflammation or the cytoskeleton, whereas decreased proteins are seen in digestive enzymes and proteins related to metabolism.1 Although more recent animal studies tend to be stricter than previous studies, Williams explains that one of the difficulties with animals studies found in the literature is that the reported proteins levels are often inconsistent with other studies.
In contrast to animal studies, pancreatitis research using human subjects has historically focused on identifying diagnostic biomarkers. These studies rely on pancreatic juices, blood, or direct sampling of pancreatic tissue. Williams suggests one way to improve future proteomics work is to make animal studies more complementary and comparable with those using human subjects. He points out that in order to find accurate biomarkers, researchers must first understand the mechanisms of disease. Another challenge when using human subjects is that the same experimental design isn’t applicable for both animals and humans. Pancreatic juices in humans, for example, react with trypsin and cause a cascade of zymogen activations that digest proteins into small pieces and render them unidentifiable. Therefore, an inhibitor or a different protease must be used in these experiments.
Another suggestion Williams makes to further pancreatitis research regards the need to increase the availability of mass spectrometry instruments and for investigators to seek out opportunities for collaborations with researchers who are knowledgeable in both mass spectrometry and in pancreas pathobiology. Williams suggests future studies be targeted at identifying and analyzing the pancreatic juice proteome in both humans and animal models. He also suggests experiments to analyze pancreatic organelles, enzymes and acini, as well as evaluating the phosphoproteome. As a whole, researchers should take a systems-wide approach to the study of pancreatitis by drawing on information from relevant metabolic pathways.
1. Williams, J.A. (2013, August) “Proteomics as a Systems Approach to Pancreatitis,” Pancreas, 42(6) (pp. 905–11), doi: 10.1097/MPA.0b013e31828fddc3.
2. Yu, J.H., Yun, S.Y., and Lim, J.W. (2003) “Proteome analysis of rat pancreatic acinar cells: Implication for cerulean-induced acute pancreatitis,” Proteomics, 3(12) (pp. 2446–53).
3. Lassout, O., et al. (2010) “Analysis of the pancreatic low molecular weight proteome in an animal model of acute pancreatitis,” Journal of Proteome Research, 9(9) (pp. 4535–44).
Post Author: Emily Humphreys. As an undergraduate studying biology at the University of Utah, Emily balanced a heavy class schedule while working long hours in a lab studying eye development. Following graduation, she became involved in infectious disease and aging research involving SNPS.
While she enjoyed the thrill of research, Emily has since traded bench work for science journalism.
She has spent the last year writing about new developments involved in proteomics research, and now food testing.
When she isn’t writing,she can be found playing outside with her kids.