Correlation between secretin-enhanced MRCP findings and histopathologic severity of chronic pancreatitis in a cat model

BACKGROUND/OBJECTIVES

To evaluate the usefulness of secretin-enhanced magnetic resonance cholangiopancreatography (S-MRCP) in chronic pancreatitis (CP), we compared the severity of disease determined histopathologically with that indicated by S-MRCP imaging parameters in an induced CP cat model.

MATERIALS AND METHODS

An experimental group of randomly chosen cats (n = 24) underwent ligation of the pancreatic duct to induce CP, and cats in a similarly chosen control group (n = 8) were sham-operated. MRCP was performed prior to secretin stimulation, and 5 and 15 min afterward, noting in particular the pancreatic duct caliber change (PDC) and the increasing degree of fluid volume (IDFV). Histopathological changes were observed in pancreatic samples processed for hematoxylin-eosin and Sirius red staining, and CP was classified as normal, minimal, moderate, or advanced. Correlations were investigated between these groups and the PDC at 5 min and the IDFV at 15 min.

RESULTS

Between cats with minimal CP and the controls, the differences in mean IDFV and PDC were not significant although diseased cats showed a downward trend in both parameters. However, compared with the control group both the mean IDFV and PDC were significantly lower in cats with moderate (IDFV, P = 0.001; PDC, P = 0.013) or advanced (IDFV, P = 0.013; PDC, P = 0.001) CP.

CONCLUSION

The S-MRCP parameters IDFV and PDC correlated with the histopathological severity of induced CP. S-MRCP could be used to evaluate the severity of CP, although it is somewhat insensitive for depicting very early disease.

Post-translational modifications of pancreatic fluid proteins collected via the endoscopic pancreatic function test (ePFT)

BACKGROUND

Early diagnosis of chronic pancreatitis by mass spectrometry-based proteomics may result in therapies to retard or modify disease progression. We aimed to identify differences in posttranslational modifications (PTMs) in pancreatic fluid proteins from individuals with chronic pancreatitis (n=9) and non-pancreatitis controls (n=9).

METHODS

We collected proteomic data from pancreatic fluid using mass spectrometry techniques. We performed database searches with emphasis on PTMs using ProteinPilot. We compared the frequency of specific PTMs in pancreatic fluid between cohorts and also to those identified in bile, gastroduodenal fluid, urine, and pancreatic duct and stellate cell lysates.

RESULTS

We identified 97 PTMs in endoscopically-collected pancreatic fluid, of which 11 were identified exclusively in one cohort and 9 others were significantly different in frequency between cohorts. Comparing pancreatic fluid with other specimens revealed differences in specific PTM frequencies, indicating that the identified PTMs were not merely artifacts of sample processing.

CONCLUSIONS

We determined PTMs of proteins extracted from pancreatic fluid which differed in frequency in chronic pancreatitis patients verses controls. Such PTMs may serve as biomarker candidates of chronic pancreatitis upon validation with larger cohorts. The analysis of the PTM profile of pancreatic fluid proteins offers an alternative method to standard protein-based biomarker discovery.

BIOLOGICAL SIGNIFICANCE

The early diagnosis of chronic pancreatitis is paramount in developing strategies to modify, retard, or halt disease progression. In the present study, we compared post-transitional modifications (PTMs) of proteins extracted from pancreatic fluid of chronic pancreatitis patients verses a control cohort. With many mass spectrometry-based proteomics workflows aimed to identify and quantify proteins, data for PTMs typically comes gratis, in that such data are collected during protein sequencing and, as such, require only downstream bioinformatics processing. We identified a total of 20 PTMs which were exclusive to or significantly different between cohorts. Upon validation with larger cohorts and enrichment of these PTMs may serve as biomarker candidates of chronic pancreatitis. PTM profiling of pancreatic fluid proteins is complementary to standard protein-based biomarker discovery, and may be readily applied to studies of pancreatic disease. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.