Cytokine profiling of pancreatic fluid using the ePFT collection method in tandem with a multiplexed microarray assay

Construct Validation of the Dietary Inflammatory Index (DII) among Young College-Aged Women

The Dietary Inflammatory Index (DII) is designed to assess the inflammatory potential of the diet. While previous research has utilized DII among college-aged women, no study to date has validated it in this population. We conducted a construct validation of DII among 393 healthy women aged 18-31 years against a robust panel of 14 inflammatory biomarkers, including CRP, IL-1β, IL-4, IL-6, IL-10, and TNF-α, which were used in the development of DII. Three linear regression models were constructed: (1) an age-adjusted model, (2) the most parsimonious model based on likelihood ratio tests, and (3) a fully adjusted model for age, race, body mass index, waist circumference, physical activity, smoking status, and nonsteroidal anti-inflammatory drug use. DII was derived from the Harvard food frequency questionnaire and categorized into quartiles. Consistent with our hypothesis, DII was negatively and significantly associated with back-transformed IL-10 levels, confirming that a more pro-inflammatory diet was associated with lower levels of an anti-inflammatory cytokine (Model 3: Q4 vs. Q1 β = 0.62; 95% CI: 0.42, 0.93; p-trend = 0.04). While validated in other populations, DII may not be a suitable tool for assessing the inflammatory potential of the diet among college-aged women.

Delayed Processing of Secretin-Induced Pancreas Fluid Influences the Quality and Integrity of Proteins and Nucleic Acids

OBJECTIVES

Endoscopic pancreatic function tests are used to diagnose pancreatic diseases and are a viable source for the discovery of biomarkers to better characterize pancreatic disorders. However, pancreatic fluid (PF) contains active enzymes that degrade biomolecules. Therefore, we tested how preservation methods and time to storage influence the integrity and quality of proteins and nucleic acids.

METHODS

We obtained PF from 9 subjects who underwent an endoscopic pancreatic function test. Samples were snap frozen at the time of collection; after 1, 2, and 4 hours on ice; or after storage overnight at 4°C with or without RNase or protease inhibitors (PIs). Electrophoresis and mass spectrometry analysis determined protein abundance and quality, whereas nucleic acid integrity values determined DNA and RNA degradation.

RESULTS

Protein degradation increased after 4 hours on ice and DNA degradation after 2 hours on ice. Adding PIs delayed degradation. RNA was significantly degraded under all conditions compared with the snap frozen samples. Isolated RNA from PF-derived exosomes exhibited similar poor quality as RNA isolated from matched PF samples.

CONCLUSIONS

Adding PIs immediately after collecting PF and processing the fluid within 4 hours of collection maintains the protein and nucleic acid integrity for use in downstream molecular analyses.

Assessment of Exocrine Pancreatic Function During Endoscopy in Children

This article will review briefly the physiology of pancreatic enzyme secretion and the role of stimulated endoscopic testing for assessing exocrine pancreatic function. Published studies in both the pediatric and adult literature are reviewed. The technique and utility of endoscopic pancreatic function testing as the method of choice in the differential diagnosis of pancreatic disorders in childhood is described. Finally, emerging, clinically useful markers that can be measured in the pancreatic fluid will be described.

Accelerating the Drug Delivery Pipeline for Acute and Chronic Pancreatitis: Summary of the Working Group on Drug Development and Trials in Recurrent Acute Pancreatitis at the National Institute of Diabetes and Digestive and Kidney Diseases Workshop

Recurrent acute pancreatitis (RAP) is a complex clinical syndrome with significant morbidity, unpredictable outcomes, and limited treatment options. The National Institute of Diabetes and Digestive and Kidney Disease sponsored a workshop on July 25, 2018, in Pittsburgh, Pennsylvania, to address research gaps impeding development of effective therapies for pancreatitis. The RAP working group identified challenges to clinical progress using existing definitions, risk assessment, diagnostic and severity criteria, disease trajectories, outcomes, and research methods. Recurrent acute pancreatitis includes all the risk of acute pancreatitis and often progresses to chronic pancreatitis with variable complications of chronic pain, exocrine insufficiency, diabetes, and pancreatic cancer. However, the great variability among individuals with RAP requires better precision in defining the risks, individual episodes, as well as their frequency, pathogenic pathways, and specific outcome measures for each of the systems affected by pancreatic inflammation. Because of disease complexity, few patients are similar enough for traditional studies and methods to conduct clinical trials with small sample sizes are required. The need for genetic testing, biomarker development, and better imaging methods was highlighted. Adaptive and N-of-one study designs, better endpoints, and outcome measures including patient-reported outcomes should considered early in developing future therapeutic trial design and include all stakeholders.

Local and Systemic Expression of Immunomodulatory Factors in Chronic Pancreatitis

Inflammatory and fibrotic events that drive chronic pancreatitis (CP) are likely orchestrated via signaling of soluble cytokines and chemokines systemically and within the pancreas. However, a comprehensive summary of the expression of such factors during CP has not been reported to date. This information is important given continued interest in targeting cytokines that influence CP pathogenesis. Reported data on the expression change of soluble immunomodulatory factors in human CP patients were identified via a literature search using a single search term. Thirty-one articles meeting the prespecified inclusion criteria were identified to generate a compiled data summary. Compiled data demonstrated up-regulation of several factors in the blood or pancreas microenvironment of CP patients. Nine factors were elevated in both compartments, including fractalkine, IFN-γ, interleukin 1β, IL-6, IL-8, macrophage inhibitory cytokine 1, neutrophil gelatinase-associated lipocalin, transforming growth factor β, and tumor necrosis factor α. Most up-regulated factors could be classified into one of several functional groups, including inflammation, chemotaxis, angiogenesis, bone remodeling, extracellular matrix remodeling, and pain. After further validation, these factors may be used as biomarkers for disease diagnosis and identification of comorbidities, or as potential therapeutic targets.

Safety of Secretin Administration in Children

OBJECTIVE

The aim of this study was to compare the hemodynamic parameters from the anesthesia records of children who underwent upper gastrointestinal endoscopy (esophagogastroduodenoscopy [EGD]) with and without secretin pancreatic function tests (sPFTs).

METHODS

The hemodynamic parameters were retrieved from an electronic anesthesia database. The secretin group consisted of 186 children, and the age- and sex-matched control group included 136 patients who did not have sPFTs.

RESULTS

There was no difference in the demographic parameters (age and sex) between the 2 groups. The secretin group had a lower height and body mass index. The sPFT resulted in an average 3-minute extension of the endoscopic procedure. The heart rate increased during the EGD in both groups and was higher (averaged 7 beats per minute) in the secretin group than the EGD-only group. There were mild elevations on the systolic and diastolic blood pressures. None of these changes were clinically significant. There were no complications reported during the anesthesia and procedures in the 2 groups.

CONCLUSIONS

Secretin PFT is a safe procedure. It only slightly prolongs the total procedure and anesthesia time. There were no clinically significant changes in the vital parameters in the secretin group, and there were no adverse effects recorded.

Endoscopic Pancreas Fluid Collection: Methods and Relevance for Clinical Care and Translational Science

Pancreatic secretions have an important role in the regulation of a normal nutritional state but can be altered owing to a variety of pathophysiological mechanisms in the context of exocrine pancreatic disease. The development of an endoscopic technique for collection of pancreatic fluid, termed endoscopic pancreatic function testing, has led to improved understanding of these alterations and is particularly helpful to characterize chronic pancreatitis. In addition, investigators have found endoscopically collected pancreatic fluid to be a valuable biofluid for the purposes of translational science. Techniques such as proteomic, cytokine, genetic mutation, DNA methylation, and microRNA analyses, among others, can be utilized to gain a better understanding of the molecular characteristics of chronic pancreatitis and other pancreatic diseases. Endoscopic collection of pancreatic fluid is safe and relatively straightforward, permitting opportunities for longitudinal analysis of these translational markers throughout the course of disease. This manuscript summarizes our current knowledge of pancreatic fluid, with an emphasis on proper techniques for sample collection and handling, its clinical utility, and preliminary observations in translational science.

Bioanalytical chemistry of cytokines--a review

Cytokines are bioactive proteins produced by many different cells of the immune system. Due to their role in different inflammatory disease states and maintaining homeostasis, there is enormous clinical interest in the quantitation of cytokines. The typical standard methods for quantitation of cytokines are immunoassay-based techniques including enzyme-linked immusorbent assays (ELISA) and bead-based immunoassays read by either standard or modified flow cytometers. A review of recent developments in analytical methods for measurements of cytokine proteins is provided. This review briefly covers cytokine biology and the analysis challenges associated with measurement of these biomarker proteins for understanding both health and disease. New techniques applied to immunoassay-based assays are presented along with the uses of aptamers, electrochemistry, mass spectrometry, optical resonator-based methods. Methods used for elucidating the release of cytokines from single cells as well as in vivo collection methods are described.

Carboxyl-ester lipase maturity-onset diabetes of the young is associated with development of pancreatic cysts and upregulated MAPK signaling in secretin-stimulated duodenal fluid

Carboxyl-ester lipase (CEL) maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes and pancreatic exocrine dysfunction due to mutations in the CEL gene encoding CEL. The pathogenic mechanism for diabetes development is unknown. Since CEL is expressed mainly in pancreatic acinar cells, we asked whether we could find structural pancreatic changes in CEL-MODY subjects during the course of diabetes development. Furthermore, we hypothesized that the diseased pancreas releases proteins that are detectable in pancreatic fluid and potentially reflect activation or inactivation of disease-specific pathways. We therefore investigated nondiabetic and diabetic CEL-mutation carriers by pancreatic imaging studies and secretin-stimulated duodenal juice sampling. The secretin-stimulated duodenal juice was studied using cytokine assays, mass spectrometry (MS) proteomics, and multiplexed MS-based measurement of kinase activities. We identified multiple pancreatic cysts in all eight diabetic mutation carriers but not in any of the four nondiabetic mutation carriers or the six healthy controls. Furthermore, we identified upregulated mitogen-activated protein kinase (MAPK) target proteins and MAPK-driven cytokines and increased MAPK activity in the secretin-stimulated duodenal juice. These findings show that subjects with CEL-MODY develop multiple pancreatic cysts by the time they develop diabetes and that upregulated MAPK signaling in the pancreatic secretome may reflect the pathophysiological development of pancreatic cysts and diabetes.

Cigarette smoking impairs pancreatic duct cell bicarbonate secretion

OBJECTIVE

To compare pancreatic duct cell function in smokers (current and past) and never smokers by measurement of secretin-stimulated peak bicarbonate concentration ([HCO3-]) in endoscopic collected pancreatic fluid (PF).

METHODS

This retrospective study was cross-sectional in design, recording demographic information (age, gender, etc.), smoking status (former, current, never), alcohol intake, clinical data (imaging, endoscopy), and laboratory results (peak PF [HCO3-]) from subjects evaluated for pancreatic disease at a tertiary pancreas center. Univariate and multivariate statistical analysis (SAS Version 9.2, Cary, NC, USA) was performed to assess the relationship between cigarette smoking and secretin-stimulated pancreatic fluid bicarbonate concentration.

RESULTS

A total of 131 subjects underwent pancreatic fluid collection (endoscopic pancreatic function test, ePFT) for bicarbonate analysis: 25.2% (33 out of 131) past smokers, 31.3% (41 out of 131) current smokers, and 43.5% (57 out of 131) were never smokers. Measures of Association: The mean peak PF [HCO3-] in never smokers (81.3 ± 18.5 mEq/L) was statistically higher (indicating better duct cell function) when compared to past smokers (66.8 ± 24.7 mEq/L, P=0.005) and current smokers (70.0 ± 20.2 mEq/L, P=0.005). However, the mean peak [HCO3-] in past smokers was not statistically different from that in current smokers (P=0.575), and therefore, the two smoking groups were combined to form a single "smokers cohort". When compared to the never smokers, the smokers cohort was older (P=0.037) and had a greater proportion of subjects with definite chronic pancreatitis imaging (P=0.010), alcohol consumption ≥20 g/day (P=0.012), and abnormal peak PF [HCO3-] (P<0.001). Risk-Based Estimates: Cigarette smoking (risk ratio, RR: 2.2, 95% CI: 1.3-3.5; P<0.001), diagnosis of definite chronic pancreatitis imaging (RR: 2.2, 95% CI: 1.6-3.2; P<0.001) and alcohol consumption ≥20 g/day (RR: 1.6, 95% CI: 1.1-2.4; P=0.033) were all associated with low mean peak PF [HCO3-] (indicating duct cell secretory dysfunction). Multivariate Analysis: Smoking (odds ratio, OR: 3.8, 95% CI: 1.6-9.1; P=0.003) and definite chronic pancreatitis imaging (OR: 5.7, 95% CI: 2.2-14.8; P<0.001) were determined to be independent predictors of low peak PF [HCO3-], controlling for age, gender, and alcohol intake. Furthermore there was no interaction between smoking status and alcohol intake in predicting duct cell dysfunction (P=0.571).

CONCLUSION

Measurement of pancreatic fluid bicarbonate in smokers reveals that cigarette smoking (past and current) is an independent risk factor for pancreatic duct cell secretory dysfunction (low PF [HCO3-]). Furthermore, the risk of duct cell dysfunction in subjects who smoked was approximately twice the risk (RR: 2.2) in never smokers. Further in depth, translational research approaches to pancreatic fluid analysis may help unravel mechanisms of cigarette smoking induced pancreatic duct cell injury.

Differentiating Branch Duct and Mixed IPMN in Endoscopically Collected Pancreatic Cyst Fluid via Cytokine Analysis

Background. Differentiating branch duct from mixed intraductal papillary mucinous neoplasm (BD-IPMN) is problematic, but clinically important as mixed IPMNs are managed surgically, while some BD-IPMN may be followed. Inflammatory mediator proteins (IMPs) have been implicated in acute and chronic inflammatory and malignant pancreatic diseases. Aim. To compare IMP profile of pancreatic cyst fluid collected endoscopically from BD-IPMN and mixed IPMN. Methods. Pancreatic cyst fluid from ten patients (5 BD-IPMN and 5 mixed IPMN) was collected by endoscopic ultrasound-guided fine needle aspiration or endoscopic retrograde cholangiopancreatography. Concentrations of 89 IMPs in these samples were determined using a multiplexed bead-based microarray protein assay and compared between BD-IPMN and mixed IPMN. Results. Eighty-six of 89 IMPs were detected in at least one of the 10 samples. Fourteen IMPs were detected only in mixed IPMN, while none were only in BD-IPMN. Of these, TGF-β1 was most prevalent, present in 3 of 5 mixed IPMNs. Seventy-two IMPs were detected in both BD-IPMN and mixed IPMNs. Of these, only G-CSF (P < 0.05) was present in higher concentrations in mixed IPMNs. Conclusion. TGF-β1 and G-CSF detected in endoscopically collected pancreatic cyst fluid are potential diagnostic biomarkers capable of distinguishing mixed IPMN from BD-IPMN.

Inflammatory protein profiling of pancreatic cyst fluid using EUS-FNA in tandem with cytokine microarray differentiates between branch duct IPMN and inflammatory cysts

BACKGROUND

Diagnosis of pancreatic cystic neoplasms remains problematic. We hypothesize that inflammatory mediator proteins in pancreatic cyst fluid can differentiate branch duct intraductal papillary mucinous neoplasms (BD-IPMNs) and pancreatic inflammatory cysts. We aim to 1) detect inflammatory mediator proteins (IMPs) using a multiplexed IMP-targeted microarray in pancreatic cyst fluid obtained during endoscopic ultrasound fine needle aspiration (EUS-FNA) and 2) compare IMP profiles in pancreatic cyst fluid from BD-IPMNs and inflammatory cysts. Pancreatic cyst fluid from ten patients (5 BD-IPMN and 5 inflammatory cysts) was obtained by EUS-FNA and analyzed directly with a multiplexed microarray assay to determine concentrations of 89 IMPs. Statistical analysis was performed using non-parametric methods.

RESULTS

Eighty-three of the 89 assayed IMPs were detected in at least one of the 10 patient samples. Seven IMPs were detected in BD-IPMN but not inflammatory cysts, while eleven IMPs were identified in inflammatory cysts but not BD-IPMN. Notably, granulocyte-macrophage colony-stimulating factor (GM-CSF) expression was present in all five inflammatory cyst samples. Hepatocyte growth factor (HGF) was present in significantly higher concentrations in inflammatory cysts compared to BD-IPMN.

CONCLUSION

Our exploratory analysis reveals that GM-CSF and HGF in EUS-FNA-collected pancreatic cyst fluid can distinguish between BD-IPMN and inflammatory cyst. Coupling microarray molecular techniques to EUS-FNA may represent a major step forward to our understanding complex pancreatic disease.

Conditional IL-2 Gene Deletion: Consequences for T Cell Proliferation

To explore the role of interleukin-2 (IL-2) in T cell proliferation, and to circumvent the IL-2 deficiency autoimmune syndrome of conventional il2 gene deletion, mice were created to allow conditional il2 gene deletion when treated with the estrogen analog, tamoxifen (TAM) as adults. Splenocytes from four different mouse strains, C57Bl/6 wild type (WT), conventional IL-2(−/−), TAM-treated Cre recombinase-negative (Cre−)/IL2fl/fl, and Cre recombinase-positive (Cre+)/IL2fl/fl, were activated with anti-CD3 and anti-CD28, and monitored for CD4+ and CD8+ T cell lymphocyte blastogenesis, aerobic glycolysis, BrdU incorporation into newly synthesized DNA, and CFSE dye dilution to monitor cell division. IL-2 production was monitored by quantitative ELISA and multiple additional cytokines were monitored by quantitative protein-bead arrays. Splenocytes from conventional IL-2(−/−) and TAM-treated Cre+ mice resulted in undetectable IL-2 production by ELISA, so that both strains were IL-2-deficient. As monitored by flow cytometry, activated CD4+ and CD8+ T cells from WT, Cre+, and Cre− mice all underwent blastogenesis, whereas far fewer cells from conventional IL-2(−/−) mice did so. By comparison, only cells from IL-2 sufficient WT and Cre− mice switched to aerobic glycolysis as evidenced by a drop in media pH. Blastogenesis was mirrored by BrdU incorporation and CFSE dye dilution by CD4+ and CD8+ T cells from WT, Cre+, and Cre− mice, which were all equivalent, while proliferation of cells from conventional IL-2(−/−) mice was compromised. Splenocytes from IL-2 deficient conventional IL-2(−/−) mice produced low or undetectable other γ_c-chain cytokines (IL-4, IL-7, IL-9, IL-13, IL-15, and IL-21), whereas production of these γ_c-chain cytokines from IL-2-deficient conditional IL-2(−/−) Cre+ mice were comparable with WT and Cre− mice. These results indicate that CD4+ and CD8+ T cell blastogenesis cannot be attributable to IL-2 alone, but a switch to aerobic glycolysis was attributable to IL-2, and proliferation after CD3/CD28 activation is dependent on γ_c-chain cytokines, and not CD3/28 triggering per se.

Proteomic analysis of formalin-fixed paraffin-embedded pancreatic tissue using liquid chromatography tandem mass spectrometry

OBJECTIVES

FFPE tissue is a standard method of specimen preservation for hospital pathology departments. Formalin-fixed paraffin-embedded tissue banks are a resource of histologically characterized specimens for retrospective biomarker investigation. We aim to establish liquid chromatography coupled with tandem mass spectrometry analysis of FFPE pancreatic tissue as a suitable strategy for the study of the pancreas proteome.

METHODS

We investigated the proteomic profile of FFPE pancreatic tissue specimens, using liquid chromatography coupled with tandem mass spectrometry, from 9 archived specimens that were histologically classified as normal (n = 3), chronic pancreatitis (n = 3), and pancreatic cancer (n = 3).

RESULTS

We identified 525 nonredundant proteins from 9 specimens. Implementing our filtering criteria, 78, 15, and 21 proteins were identified exclusively in normal, chronic pancreatitis, and pancreatic cancer specimens, respectively. Several proteins were identified exclusively in specimens with no pancreatic disease: spink 1, retinol dehydrogenase, and common pancreatic enzymes. Similarly, proteins were identified exclusively in chronic pancreatitis specimens: collagen α1 (XIV), filamin A, collagen α3 (VI), and SNC73. Proteins identified exclusively in pancreatic cancer included annexin 4A and fibronectin.

CONCLUSIONS

We report that differentially expressed proteins can be identified among FFPE tissue specimens originating from individuals with different pancreatic histologic findings. The mass spectrometry-based method used herein has the potential to enhance biomarker discovery and chronic pancreatitis research.