Proteomic analysis of heat shock-induced protection in acute pancreatitis

Temporal Proteomic and Lipidomic Profiles of Cerulein-Induced Acute Pancreatitis Reveal Novel Insights for Metabolic Alterations in the Disease Pathogenesis

The pathophysiological mechanisms of acute pancreatitis (AP) are complex and have remained a mystery to date, but metabolism is gradually recognized as an important driver of AP onset and development. We used a cerulein-induced AP mouse model to conduct liquid chromatography-mass spectrometry (LC-MS/MS)-based time-course proteomics and lipidomics in order to better understand the underlying metabolic alterations linked with AP. Results showed that a series of significant changes in proteins over time with a boost in expression were enriched in lipase activity, lipoprotein, and lipids absorption and transport regulation. Furthermore, 16 proteins associated with lipid metabolism and signaling pathways together with the whole lipid species changing profile led to the vital identification of changing law in glycerides, phosphoglycerides, and free fatty acids. In addition to lipid metabolism and regulation-associated proteins, several digestive enzymes and adaptive anti-trypsin, stress response, and energy metabolism-related proteins showed an increment in abundance. Notably, central carbon and branched chain amino acid metabolism were enhanced during 0-24 h from the first cerulein stimulation. Taken together, this integrated proteomics and lipidomics revealed a novel metabolic insight into metabolites transforming rules that might be relevant to their function and drug targets investigation. (Created with Biorender.com.).

Artificial Nonenzymatic Antioxidant MXene Nanosheet-Anchored Injectable Hydrogel as a Mild Photothermal-Controlled Oxygen Release Platform for Diabetic Wound Healing

Hypoxia, excessive reactive oxygen species (ROS), impaired angiogenesis, lasting inflammation, and bacterial infection, are key problems impeding diabetic wound healing. Particularly, controllable oxygen release and ROS scavenging capacities are critical during the wound healing process. Here, an injectable hydrogel based on hyaluronic acid-graft-dopamine (HA-DA) and polydopamine (PDA) coated Ti₃C₂ MXene nanosheets is developed catalytically cross-linked by an oxyhemoglobin/hydrogen (HbO₂/H₂O₂) system combined with mild photothermal stimulation for diabetic wound healing. HbO₂ not only acts as a horseradish peroxidase-like to catalyze the hydrogel formation but also as an oxygen carrier to controllably release oxygen when activated by the mild heat produced from near-infrared (NIR) irradiation. Specifically, HbO₂ can provide oxygen repeatedly by binding oxygen in the air when the NIR is off. The stable photoresponsive heating behavior of MXene ensures the repeatable oxygen release. Additionally, artificial nonenzymatic antioxidant MXene nanosheets are proposed to scavenge excessive reactive nitrogen species and ROS including H₂O₂, O₂^•-, and ^•OH, keeping the intracellular redox homeostasis and alleviating oxidative stress, and eradicate bacteria to avoid infection. The antioxidant and antibacterial abilities of MXene are further improved by PDA coating, which also promotes the MXene nanosheets cross-linking into the network of the hydrogel. HA-DA molecules endow the hydrogel with the capacity to regulate macrophage polarization from M1 to M2 to achieve anti-inflammation. More importantly, the MXene-anchored hydrogel with multifunctions including tissue adhesion, self-healing, injectability, and hemostasis, combined with mild photothermal stimulation, greatly promotes human umbilical vein endothelial cell proliferation and migration and notably facilitates infected diabetic wound healing.

Improved Integrated Whole Proteomic and Phosphoproteomic Profiles of Severe Acute Pancreatitis

Severe acute pancreatitis (SAP) is caused by complicated biological factors, and revealing its complex pathogenesis by single-target analysis is difficult. Systematic studies have developed slowly because extraction of degradable pancreatic proteins exposed to multiple proteases is challenging. We present integrated whole proteomic and phosphoproteomic profiles of SAP rats based on a modified protein extraction strategy with less protein degradation. Data-dependent acquisition (DDA) and data-independent acquisition (DIA) strategies were applied to select an appropriate method. Total 275 differentially expressed proteins and 757 differentially expressed phosphorylated proteins were identified by DIA-based quantitative proteomics. Several signal transduction pathways, including the AMPK, MAPK, and PI3K-Akt pathways, were enriched in SAP. Up-regulation of phosphorylated proteins involved in the process of TNFA signaling and inflammatory response was also detected in SAP. Our results improve the understanding of SAP development and progression.

A tandem mass tag (TMT) proteomic analysis during the early phase of experimental pancreatitis reveals new insights in the disease pathogenesis

Changes in the protein expression occurring within the initiation phase of acute pancreatitis (AP) might be vital in the development of this complex disease. However, the exact mechanisms involved in the onset of AP remains elusive and most of our knowledge about the pathobiology of AP comes from animal models. We performed in a rat pancreatitic model a high-throughput shotgun proteomic profiling of the soluble and whole membrane fractions from the pancreas during the early phase of cerulein (Cer)-induced AP. We identified 997 proteins, of which 353 were significantly different (22, 276 or 55 in both, the soluble or the membrane fractions, respectively). Gene Ontology and KEGG PATHWAY analyses revealed that these proteins were implicated in molecular mechanisms relevant to AP pathogenesis, including vesicle-mediated and protein transport, lysosomal and mitochondrial impairment or proteolysis. Numerous metabolic processes were downregulated apparently to reduce energy consumption, and a remarkable increase in inflammatory and stress responses was also highlighted. The proteomic data were verified by immunoblotting of 11 and 7 different soluble or membrane-associated proteins, either novel (VPS29 and MCTS1) or known factors in AP. Also, our first observation of the imbalance of some COP proteins during AP early phase deserves further characterization.

BIOLOGICAL SIGNIFICANCE

AP is one of the most important pathological inflammatory states of the exocrine pancreas but its pathophysiology remains incompletely understood, especially the early acinar events. Proteomic analysis of pancreatic subcellular fractions simplifies protein maps and helps in the identification of new protein alterations and biomarkers characterizing pancreatic tissue damage. Our shotgun approach has not been previously used to profile the early proteomic alterations of the disease, which are considered crucial for its development and for the founding of clinical procedures. Furthermore, our subcellular fractionation protocol allowed us to detect changes in membrane proteins so far overlooked in the proteomic study of AP. Accordingly, using TMT proteomics and bioinformatic tools, we were able to detect significant changes in protein expression related to many pathobiological pathways of acute pancreatitis as from the early phase of the disease. To our knowledge, some of these changes, such as the imbalance of some COP proteins, have never been described in this disease.

Laser Capture Microdissection of Pancreatic Acinar Cells to Identify Proteomic Alterations in a Murine Model of Caerulein-Induced Pancreatitis

Objectives:

Chronic pancreatitis (CP) is characterized by inflammation and fibrosis of the pancreas, leading to pain, parenchymal damage, and loss of exocrine and endocrine function. There are currently no curative therapies; diagnosis remains difficult and aspects of pathogenesis remain unclear. Thus, there is a need to identify novel biomarkers to improve diagnosis and understand pathophysiology. We hypothesize that pancreatic acinar regions contain proteomic signatures relevant to disease processes, including secreted proteins that could be detected in biofluids.

Methods:

Acini from pancreata of mice injected with or without caerulein were collected using laser capture microdissection followed by mass spectrometry analysis. This protocol enabled high-throughput analysis that captured altered protein expression throughout the stages of CP.

Results:

Over 2,900 proteins were identified, whereas 331 were significantly changed ≥2-fold by mass spectrometry spectral count analysis. Consistent with pathogenesis, we observed increases in proteins related to fibrosis (e.g., collagen, P<0.001), several proteases (e.g., trypsin 1, P<0.001), and altered expression of proteins associated with diminished pancreas function (e.g., lipase, amylase, P<0.05). In comparison with proteomic data from a public data set of CP patients, a significant correlation was observed between proteomic changes in tissue from both the caerulein model and CP patients (r=0.725, P<0.001).

CONCLUSIONS:

This study illustrates the ability to characterize proteome changes of acinar cells isolated from pancreata of caerulein-treated mice and demonstrates a relationship between signatures from murine and human CP.

Acute pancreatitis: The stress factor

Acute pancreatitis is an inflammatory disorder of the pancreas that may cause life-threatening complications. Etiologies of pancreatitis vary, with gallstones accounting for the majority of all cases, followed by alcohol. Other causes of pancreatitis include trauma, ischemia, mechanical obstruction, infections, autoimmune, hereditary, and drugs. The main events occurring in the pancreatic acinar cell that initiate and propagate acute pancreatitis include inhibition of secretion, intracellular activation of proteases, and generation of inflammatory mediators. Small cytokines known as chemokines are released from damaged pancreatic cells and attract inflammatory cells, whose systemic action ultimately determined the severity of the disease. Indeed, severe forms of pancreatitis may result in systemic inflammatory response syndrome and multiorgan dysfunction syndrome, characterized by a progressive physiologic failure of several interdependent organ systems. Stress occurs when homeostasis is threatened, and stressors can include physical or mental forces, or combinations of both. Depending on the timing and duration, stress can result in beneficial or harmful consequences. While it is well established that a previous acute-short-term stress decreases the severity of experimentally-induced pancreatitis, the worsening effects of chronic stress on the exocrine pancreas have received relatively little attention. This review will focus on the influence of both prior acute-short-term and chronic stress in acute pancreatitis.

Proteomics as a systems approach to pancreatitis

Proteomics is an approach to looking at the identity, amount, proteolysis, compartmentalization, and posttranslational modification of a large number of proteins simultaneously in a cell or tissue. Recently, proteomics has begun to be applied to the study of pancreatitis to ascertain mechanisms of disease and search for biomarkers of disease. Most mechanistic work has been carried out in animal models of acute pancreatitis. In 8 studies, 97 proteins have been reported to increase, 55 to decrease, and 23 to undergo proteolysis. Proteins showing increases are most often related to stress, inflammation, or the cytoskeleton, whereas decreases are seen in digestive enzymes and proteins related to metabolism. Many protein changes however, are not consistent between studies and only the most recent studies are rigorous and quantitative. By contrast, biomarker studies have focused on pancreatic juice and plasma of humans with disease and often are directed at distinguishing chronic pancreatitis from cancer. Chronic pancreatitis has also been investigated in tissue sections of histological samples. In this review, the results of studies to date are described as well as coverage of the methods used and special issues that must be considered. Areas are pointed out that are worthy of future study.

An integrated approach for comparative proteomic analysis of human bile reveals overexpressed cancer-associated proteins in malignant biliary stenosis

Proteomics is a key tool in the identification of new bile biomarkers for differentiating malignant and nonmalignant biliary stenoses. Unfortunately, the complexity of bile and the presence of molecules interfering with protein analysis represent an obstacle for quantitative proteomic studies in bile samples. The simultaneous need to introduce purification steps and minimize the use of pre-fractionation methods inevitably leads to protein loss and limited quantifications. This dramatically reduces the chance of identifying new potential biomarkers. In the present study, we included differential centrifugation as a preliminary step in a quantitative proteomic workflow involving iTRAQ labeling, peptide fractionation by OFFGEL electrophoresis and LC-MS/MS, to compare protein expression in bile samples collected from patients with malignant or nonmalignant biliary stenoses. A total of 1267 proteins were identified, including a set of 322 newly described bile proteins, mainly belonging to high-density cellular fractions. The subsequent comparative analysis led to a 5-fold increase in the number of quantified proteins over previously published studies and highlighted 104 proteins overexpressed in malignant samples. Finally, immunoblot verifications performed on a cohort of 8 malignant (pancreatic adenocarcinoma, n=4; cholangiocarcinoma, n=4) and 5 nonmalignant samples (chronic pancreatitis, n=3; biliary stones, n=2) confirmed the results of proteomic analysis for three proteins: olfactomedin-4, syntenin-2 and Ras-related C3 botulinum toxin substrate 1. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Bile carcinoembryonic cell adhesion molecule 6 (CEAM6) as a biomarker of malignant biliary stenoses

Differentiating malignant from nonmalignant biliary stenoses is challenging. This could be facilitated by the measurement of cancer biomarkers in bile. We aimed at (i) identifying new cancer biomarkers by comparative proteomic analysis of bile collected from patients with a malignant or benign biliary stenosis (exploratory phase) and (ii) verifying the accuracy of the newly identified potential biomarkers for discriminating malignant versus nonmalignant biliary stenoses in a larger group of patients (confirmation phase). Overall, 66 proteins were found overexpressed (ratio>1.5) in at least one cancer condition using proteomic analysis and 7 proteins were increased in all malignant/nonmalignant disease comparisons. Preliminary screening by immunoblot highlighted carcinoembryonic cell adhesion molecule 6 (CEAM6), a cell surface protein overexpressed in many human cancers, as an interesting candidate biomarker. ELISA subsequently confirmed CEAM6 as a potential bile biomarker for distinguishing malignant from benign biliary stenoses with a receiver operating characteristic (ROC) area under the curve (AUC) of 0.92 (specificity 83%, sensitivity 93%, positive predictive value 93%, and negative predictive value 83%). No significant difference in serum CEAM6 level was found between malignant and nonmalignant samples. Combining bile CEAM6 and serum CA19-9 in a panel further improved diagnostic accuracy for malignant stenoses (AUC 0.96, specificity 83%, sensitivity 97%, positive predictive value 93%, and negative predictive value 91%). CEAM6 measurement in bile could be clinically useful to discriminate between malignant and nonmalignant causes of biliary stenosis. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Time-course proteomic analysis of taurocholate-induced necrotizing acute pancreatitis

Acute pancreatitis is an inflammatory disease of the pancreas, which varies greatly in course and severity. Severe forms are associated with serious local and/or systemic complications, and eventually death. The pathobiology of acute pancreatitis is complex. Animal models have been developed to investigate pathobiological processes and identify factors determining disease course. We performed a time-course proteomic analysis using a rat model of severe necrotizing acute pancreatitis induced by taurocholate perfusion in the pancreatic ducts. Results showed that levels of proteins associated to a given biological process changed in a coordinated fashion after disease onset. It was possible to follow the response of a particular pathobiological process to pancreatitis induction and to compare the course of protein pathways. Proteins involved in acinar cell secretion were found to follow a different kinetics than other cellular processes. After an initial decrease, secretory pathway-associated proteins raised again at 18 h post-induction. This phenomenon coincided with a burst in the expression of pancreatitis-associated protein (REG3A), an acute phase protein produced by the exocrine pancreas, and with the decrease of classical markers of pancreatic injury, suggesting that the expression of proteins associated to the secretory pathway may be a modulating factor of pancreas injury.

BIOLOGICAL SIGNIFICANCE

Acute pancreatitis (AP) is a complex inflammatory disease, the pathobiology of which is not yet fully understood. Various animal models, relying on different mechanisms of disease induction, have been developed in order to investigate pathobiological processes of AP. In this study, we performed a time-course proteomic analysis to investigate changes of the pancreas proteome occurring in an experimental model of AP induced by perfusion of taurocholate, a bile acid, into the pancreatic duct. This experimental model is characterized by a severe disease with pancreatic necrosis and systemic inflammation. The objectives of this study were to determine the kinetics of functionally related proteins in the early steps of the experimental disease in order to identify protein pathways playing key roles in AP pathobiology and to correlate these data with parameters classically used to assess disease severity. The present work provides for the first time an overview of protein expression in the pancreas during the course of taurocholate-induced necrotizing AP. We believe that correlation of these results with data obtained using proteomic or biochemical approaches in various experimental models of AP will help in highlighting new features, generating hypotheses and constitute therefore a strong and reliable basis for further targeted investigations.

Effects of Chai-Qin-Cheng-Qi decoction () on acute pancreatitis-associated lung injury in mice with acute necrotizing pancreatitis

OBJECTIVE: To investigate the effects of Chai-Qin-Cheng-Qi Decoction (, CQCQD) on acute pancreatitis-associated lung injury in mice with acute necrotizing pancreatitis (ANP). METHODS: Thirty healthy mice were randomly divided into three groups: an ANP group (ANP+placebo, n=10); a treatment group (ANP+CQCQD, n=10); and a control group (normal mice+placebo, n=10). ANP was induced by intraperitoneal injection with 8% L-arginine (4 μg/kg), and the control group was injected with normal saline. The treatment group received CQCQD (20 mL/kg), and the ANP and control groups received placebo (sucrose and starch) intragastrically at 2 h intervals. After the third intragastric administration, blood, pancreatic tissues and right lung tissues were collected for measurement of serum interleukin-6 (IL-6) and interleukin-10 (IL-10) by enzyme-linked immunosorbent assay, and the expression of heat shock protein 70 (HSP70) in lung tissue was determined by Western blot analysis. Pathological changes of pancreatic tissue and lung tissue were examined. RESULTS: Serum IL-6 was significantly higher in the ANP group compared with the control and the treatment groups (1589.63±377.28 vs. 927.46±210.42 pg/mL, P<0.05, and 1589.63±377.28 vs. 1107.73±351.62 pg/mL, P<0.05, respectively). The IL-10 concentration was significantly lower in the ANP group compared with the treatment group (920.64±101.68 vs. 1177.84±201.72 pg/mL, P<0.05), but no signififi cant difference was found between the ANP and control groups and between the treatment and control groups. The expression level of HSP70 in the ANP and control groups was signififi cantly lower than in the treatment group (0.93±0.03 vs. 1.42±0.21, P<0.01, and 0.81±0.09 vs. 1.42±0.21, P<0.01, respectively). There was no signififi cant difference in HSP70 levels between the ANP and control groups. Histological scores of pancreatic and lung tissue were significantly decreased in the treatment group compared with the ANP groups (4.50±0.54 vs. 6.20±1.65, P<0.05, and 3.00±0.63 vs. 3.87±0.83, P<0.05, respectively). CONCLUSIONS: The incidence of acute pancreatitisassociated lung injury in ANP mice correlates positively with serum IL-6 concentration. CQCQD may inhibit IL-6 induction and increase IL-10 concentration and HSP70 expression, effectively reducing lung injury.

Hsp72 overexpression accelerates the recovery from caerulein-induced pancreatitis

Background and Aims

Heat shock protein (Hsp) 72 is a molecular chaperone which is upregulated in response to a variety of stress situations and has a general cytoprotective function. Increased Hsp72 levels were implicated in protection from acute pancreatitis; a hypothesis which was not tested in a transgenic mouse model yet.

Methods

To analyze the role of Hsp72 during acute pancreatitis, well-characterized transgenic animals overexpressing rat Hsp72 (Hsp72 mice) under the control of the ß-actin promoter were subjected to caerulein- and L-arginine-induced acute pancreatitis. The severity of experimental pancreatitis was determined via serum lipase levels, morphometric evaluation and quantification of pancreatic edema/inflammation.

Results

Hsp72 mice displayed ∼100-times Hsp72 overexpression, but no changes in the remaining chaperones. Robust Hsp72 signal was observed in pancreatic acini, but not in islets or ductal cells. In both models, elevated Hsp72 did not protect from development of acute pancreatitis and the pancreatitis-associated lung injury, but accelerated recovery from caerulein-induced tissue injury (lower lipase levels, edema, inflammation and necrosis 36 h after caerulein administration). The observed protective function of Hsp72 in caerulein-induced pancreatitis is likely due to an attenuated NF-κB signalling.

Conclusions

Hsp72 overexpression accelerates the recovery from acute pancreatitis and may represent a potential treatment strategy.

Proteomic analysis of the soluble and the lysosomal+mitochondrial fractions from rat pancreas: Implications for cerulein-induced acute pancreatitis

Alterations in protein expression within the initiation phase of acute pancreatitis (AP) might play an important role in the development of this disease, lysosomes being involved in its pathophysiology. The use of pancreatic subcellular fractions in proteomic analysis, simplifies protein maps and helps in the identification of new protein changes and biomarkers characterizing tissue damage. The present study aims to determine the differentially expressed acidic proteins in the pancreatic soluble and lysosomal+mitochondrial (L+M) fractions from rats during the early phase of the experimental model of cerulein (Cer)-induced AP. Subcellular pancreatic extracts from diseased and control rats were analyzed by 2-DE (3-5.6 pH range) and MALDI-TOF/TOF MS. Comparative analysis afforded the conclusive identification of 13 (soluble fraction) and 7 (L+M fraction) proteins or protein fragments occuring in different amounts between diseased and control pancreas, some of them being newly described in AP. In the soluble fraction, we detected changes related to inflammation and apoptosis (α1-inhibitor-3, α-1 antitrypsin, α-1 macroglobulin, haptoglobin, STRAP), oxidative stress and stress response (peroxiredoxin-2, thioredoxin-like 1, GRP94/TRA1, heat shock cognate 71kDa protein), digestive proteases (elastase 3B), serine protease inhibition (serpins B6 and A3L) and translation processes (EF 1-δ). In the L+M fraction, we detected changes mainly related to energy generation or cellular metabolism (ATP synthase β subunit, chymotrypsinogen B, triacylglycerol lipase), cell redox homeostasis (iodothyronine 5´monodeiodinase) and digestive proteases (carboxypeptidase B1). The data should provide valuable information for unraveling the early pathophysiologic mechanisms of Cer-induced AP.