Monocyte chemoattractant protein 1, active carboxypeptidase B and CAPAP at hospital admission are predictive markers for severe acute pancreatitis

Mechanisms linking hypertriglyceridemia to acute pancreatitis

Hypertriglyceridemia (HTG) is a metabolic disorder, defined when serum or plasma triglyceride concentration (seTG) is >1.7 mM. HTG can be categorized as mild to very severe groups based on the seTG value. The risk of acute pancreatitis (AP), a serious disease with high mortality and without specific therapy, increases with the degree of HTG. Furthermore, even mild or moderate HTG aggravates AP initiated by other important etiological factors, including alcohol or bile stone. This review briefly summarizes the pathophysiology of HTG, the epidemiology of HTG-induced AP and the clinically observed effects of HTG on the outcomes of AP. Our main focus is to discuss the pathophysiological mechanisms linking HTG to AP. HTG is accompanied by an increased serum fatty acid (FA) concentration, and experimental results have demonstrated that these FAs have the most prominent role in causing the consequences of HTG during AP. FAs inhibit mitochondrial complexes in pancreatic acinar cells, induce pathological elevation of intracellular Ca²⁺ concentration, cytokine release and tissue injury, and reduce the function of pancreatic ducts. Furthermore, high FA concentrations can induce respiratory, kidney, and cardiovascular failure in AP. All these effects may contribute to the observed increased AP severity and frequent organ failure in patients. Importantly, experimental results suggest that the reduction of FA production by lipase inhibitors can open up new therapeutic options of AP. Overall, investigating the pathophysiology of HTG-induced AP or AP in the presence of HTG and determining possible treatments are needed.

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis

Introduction

Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities.

Methods

A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention.

Results

205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease.

Conclusions

AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

Exposure to binge ethanol and fatty acid ethyl esters exacerbates chronic ethanol-induced pancreatic injury in hepatic alcohol dehydrogenase-deficient deer mice

Alcoholic chronic pancreatitis (ACP) is a fibroinflammatory disease of the pancreas. However, metabolic basis of ACP is not clearly understood. In this study, we evaluated differential pancreatic injury in hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice fed chronic ethanol (EtOH), chronic plus binge EtOH, and chronic plus binge EtOH and fatty acid ethyl esters (FAEEs, nonoxidative metabolites of EtOH) to understand the metabolic basis of ACP. Hepatic ADH^- and ADH normal (ADH⁺) deer mice were fed Lieber-DeCarli liquid diet containing 3% (wt/vol) EtOH for 3 mo. One week before the euthanization, chronic EtOH-fed mice were further administered with an oral gavage of binge EtOH with/without FAEEs. Blood alcohol concentration (BAC), pancreatic injury, and inflammatory markers were measured. Pancreatic morphology, ultrastructural changes, and endoplasmic reticulum (ER)/oxidative stress were examined using H&E staining, electron microscopy, immunostaining, and/or Western blot, respectively. Overall, BAC was substantially increased in chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. A significant change in pancreatic acinar cell morphology, with mild to moderate fibrosis and ultrastructural changes evident by dilatations and disruption of ER cisternae, ER/oxidative stress along with increased levels of inflammatory markers were observed in the pancreas of chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. Furthermore, chronic plus binge EtOH and FAEEs exposure elevated BAC, enhanced ER/oxidative stress, and exacerbated chronic EtOH-induced pancreatic injury in ADH^- deer mice suggesting a role of increased body burden of EtOH and its metabolism under reduced hepatic ADH in initiation and progression of ACP.NEW & NOTEWORTHY We established a chronic EtOH feeding model of hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice, which mimics several fibroinflammatory features of human alcoholic chronic pancreatitis (ACP). The fibroinflammatory and morphological features exacerbated by chronic plus binge EtOH and FAEEs exposure provide a strong case for metabolic basis of ACP. Most importantly, several pathological and molecular targets identified in this study provide a much broader understanding of the mechanism and avenues to develop therapeutics for ACP.

Differential cytotoxicity, ER/oxidative stress, dysregulated AMPKα signaling, and mitochondrial stress by ethanol and its metabolites in human pancreatic acinar cells

BACKGROUND

Alcoholic chronic pancreatitis (ACP) is a serious inflammatory disorder of the exocrine pancreatic gland. A previous study from this laboratory showed that ethanol (EtOH) causes cytotoxicity, dysregulates AMPKα and ER/oxidative stress signaling, and induces inflammatory responses in primary human pancreatic acinar cells (hPACs). Here we examined the differential cytotoxicity of EtOH and its oxidative (acetaldehyde) and nonoxidative (fatty acid ethyl esters; FAEEs) metabolites in hPACs was examined to understand the metabolic basis and mechanism of ACP.

METHODS

We evaluated concentration-dependent cytotoxicity, AMPKα inactivation, ER/oxidative stress, and inflammatory responses in hPACs by incubating them for 6 h with EtOH, acetaldehyde, or FAEEs at clinically relevant concentrations reported in alcoholic subjects using conventional methods. Cellular bioenergetics (mitochondrial stress and a real-time ATP production rate) were determined using Seahorse XFp Extracellular Flux Analyzer in AR42J cells treated with acetaldehyde or FAEEs.

RESULTS

We observed concentration-dependent increases in LDH release, inactivation of AMPKα along with upregulation of ACC1 and FAS (key lipogenic proteins), downregulation of p-LKB1 (an oxidative stress-sensitive upstream kinase regulating AMPKα) and CPT1A (involved in β-oxidation of fatty acids) in hPACs treated with EtOH, acetaldehyde, or FAEEs. Concentration-dependent increases in oxidative stress and ER stress as measured by GRP78, unspliced XBP1, p-eIF2α, and CHOP along with activation of p-JNK1/2, p-ERK1/2, and p-P38MAPK were present in cells treated with EtOH, acetaldehyde, or FAEEs, respectively. Furthermore, a significant decrease was observed in the total ATP production rate with subsequent mitochondrial stress in AR42J cells treated with acetaldehyde and FAEEs.

CONCLUSIONS

EtOH and its metabolites, acetaldehyde and FAEEs, caused cytotoxicity, ER/oxidative and mitochondrial stress, and dysregulated AMPKα signaling, suggesting a key role of EtOH metabolism in the etiopathogenesis of ACP. Because oxidative EtOH metabolism is negligible in the exocrine pancreas, the pathogenesis of ACP could be attributable to the formation of FAEEs and related pancreatic acinar cell injury.

Activation of AMP-activated protein kinase attenuates ethanol-induced ER/oxidative stress and lipid phenotype in human pancreatic acinar cells

Primary toxicity targets of alcohol and its metabolites in the pancreas are cellular energetics and endoplasmic reticulum (ER). Therefore, the role of AMP-Activated Protein Kinase (AMPKα) in amelioration of ethanol (EtOH)-induced pancreatic acinar cell injury including ER/oxidative stress, inflammatory responses, the formation of fatty acid ethyl esters (FAEEs) and mitochondrial bioenergetics were determined in human pancreatic acinar cells (hPACs) and AR42J cells incubated with/without AMPKα activator [5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)]. EtOH treated hPACs showed concentration and time-dependent increases for FAEEs and inactivation of AMPKα, along with the upregulation of ACC1 and FAS (key lipogenic proteins) and downregulation of CPT1A (involved β-oxidation of fatty acids). These cells also showed significant ER stress as evidenced by the increased expression for GRP78, IRE1α, and PERK/CHOP arm of unfolded protein response promoting apoptosis and activating p-JNK1/2 and p-ERK1/2 with increased secretion of cytokines. AR42J cells treated with EtOH showed increased oxidative stress, impaired mitochondrial biogenesis, and decreased ATP production rate. However, AMPKα activation by AICAR attenuated EtOH-induced ER/oxidative stress, lipogenesis, and inflammatory responses as well as the formation of FAEEs and restored mitochondrial function in hPACs as well as AR42J cells. Therefore, it is likely that EtOH-induced inactivation of AMPKα plays a crucial role in acinar cell injury leading to pancreatitis. Findings from this study also suggest that EtOH-induced inactivation of AMPKα is closely related to ER/oxidative stress and synthesis of FAEEs, as activation of AMPKα by AICAR attenuates formation of FAEEs, ER/oxidative stress and lipogenesis, and improves inflammatory responses and mitochondrial bioenergetics.

Organ Failure Due to Systemic Injury in Acute Pancreatitis

Acute pancreatitis may be associated with both local and systemic complications. Systemic injury manifests in the form of organ failure, which is seen in approximately 20% of all cases of acute pancreatitis and defines "severe acute pancreatitis." Organ failure typically develops early in the course of acute pancreatitis, but also may develop later due to infected pancreatic necrosis-induced sepsis. Organ failure is the most important determinant of outcome in acute pancreatitis. We review here the current understanding of the risk factors, pathophysiology, timing, impact on outcome, and therapy of organ failure in acute pancreatitis. As we discuss the pathophysiology of severe systemic injury, the distinctions between markers and mediators of severity are highlighted based on evidence supporting their causality in organ failure. Emphasis is placed on clinically relevant end points of organ failure and the mechanisms underlying the pathophysiological perturbations, which offer insight into potential therapeutic targets to treat.

Obesity and pancreatitis

PURPOSE OF REVIEW

The obesity pandemic poses a unique set of problems for acute pancreatitis - both by increasing acute pancreatitis incidence, and worsening acute pancreatitis severity. This review explores these associations, underlying mechanisms, and potential therapies.

RECENT FINDINGS

We review how the obesity associated increase in gallstones, surgical, and endoscopic interventions for obesity management, diabetes, and related medications such as incretin-based therapies and hypertriglyceridemia may increase the incidence of acute pancreatitis. The mechanism of how obesity may increase acute pancreatitis severity are discussed with a focus on cytokines, adipokines, damage-associated molecular patterns and unsaturated fatty acid-mediated lipotoxicity. The role of obesity in exacerbating pancreatic necrosis is discussed; focusing on obesity-associated pancreatic steatosis. We also discuss how peripancreatic fat necrosis worsens organ failure independent of pancreatic necrosis. Last, we discuss emerging therapies including choice of intravenous fluids and the use of lipase inhibitors which have shown promise during severe acute pancreatitis.

SUMMARY

We discuss how obesity may contribute to increasing acute pancreatitis incidence, the role of lipolytic unsaturated fatty acid release in worsening acute pancreatitis, and potential approaches, including appropriate fluid management and lipase inhibition in improving acute pancreatitis outcomes.

IL-6 and CRP are superior in early differentiation between mild and non-mild acute pancreatitis

BACKGROUND

The revised Atlanta classification on acute pancreatitis (AP) presents distinct criteria for severity categorization. Due to the lack of reliable prognostic markers, a majority of patients with AP are currently hospitalized and initially managed identically. As incidence and financial costs are rising the need for early severity differentiation will increase. This study aimed to investigate the capacity of biomarkers to stratify AP patients during the initial course of the disease.

METHODS

Patients with AP were prospectively enrolled and dichotomized into mild or non-mild (moderately severe and severe AP) according to the revised Atlanta classification. Serum samples taken within 13-36 h after onset of disease were analyzed for 20 biomarkers. Through receiver operating curves cut-off levels were set for 5 biomarkers whose stratifying ability was further analyzed. Additionally, the patients were classified according to the harmless acute pancreatitis score (HAPS).

RESULTS

Among the 175 patients, 70.9% had mild and 29.1% non-mild AP. CRP and IL-6 combined, with cut-off levels 57.0 and 23.6 respectively, demonstrated superior discriminative capacity with an area under the curve of 0.803, sensitivity 98%, specificity 54% and a positive and negative likelihood ratio of 2.1 and 0.06 for the non-mild group. Regarding the mild group likelihood ratios were positive 26.5 and negative 0.48. The identification potential of the HAPS was generally inferior when compared to CRP plus IL-6.

CONCLUSIONS

In this study CRP and IL-6 demonstrate a clinically relevant capacity to differentiate mild from non-mild AP early in the course of AP.

Immunopathogenesis of pancreatitis

The conventional view of the pathogenesis of acute and chronic pancreatitis is that it is due to a genetic- or environment-based abnormality of intracellular acinar trypsinogen activation and thus to the induction of acinar cell injury that, in turn, sets in motion an intra-pancreatic inflammatory process. More recent studies, reviewed here, present strong evidence that while such trypsinogen activation is likely a necessary first step in the inflammatory cascade underlying pancreatitis, sustained pancreatic inflammation is dependent on damage-associated molecular patterns-mediated cytokine activation causing the translocation of commensal (gut) organisms into the circulation and their induction of innate immune responses in acinar cells. Quite unexpectedly, these recent studies reveal that the innate responses involve activation of responses by an innate factor, nucleotide-binding oligomerization domain 1 (NOD1), and that such NOD1 responses have a critical role in the activation/production of nuclear factor-kappa B and type I interferon. In addition, they reveal that chronic inflammation and its accompanying fibrosis are dependent on the generation of IL-33 by injured acinar cells and its downstream induction of T cells producing IL-13. These recent studies thus establish that pancreatitis is quite a unique form of inflammation and one susceptible to newer, more innovative therapy.

Predictive Capacity of Biomarkers for Severe Acute Pancreatitis

Background: Early prediction of severe acute pancreatitis (SAP) substantially improves treatment of patients. A large amount of biomarkers have been studied with this objective. The aim of this work was to study predictive biomarkers using preset cut-off levels in an unselected population of patients with acute pancreatitis (AP). Methods: 232 patients (52.2% males, median age 66 years) with AP admitted to Skåne University Hospital, Malmö, were consecutively enrolled. Blood samples were collected upon admission and clinical data were gathered both prospectively at inclusion and through review of medical notes. Cut-off levels were defined based on the reports of prior studies, and through their results eight biomarkers (IL-1β, IL-6, IL-8, IL-10, TNF-α, MCP-1, procalcitonin and D-dimer) were selected for analysis. Results: Of the patients, 83.2% had mild AP and 16.8% had SAP. Levels of IL-1β, IL-6 and IL-10 were significantly (p < 0.05) higher upon admission in the group with SAP. When applying the preset cut-off levels on our material, sensitivity and specificity for prediction of severity were low. Receiver operating characteristic curves showed that selected cut-off levels were acceptable, but areas under the curves were inferior compared to other studies. The results did not improve when using the revised Atlanta 2012 classification. Conclusions: Previous studies on severity prediction of AP are difficult to compare due to large variations in setups and outcomes. Calculated cut-offs in our cohort were in acceptable range from preset levels, however areas under the curves were low, indicating suboptimal biomarkers for the unselected population investigated. For comparable results and possible clinical implementations, future studies need large consecutive series with a reasonable percentage of severe cases. Additionally, novel biomarkers need to be explored.

Peripancreatic fat necrosis worsens acute pancreatitis independent of pancreatic necrosis via unsaturated fatty acids increased in human pancreatic necrosis collections

BACKGROUND AND AIMS

Peripancreatic fat necrosis occurs frequently in necrotising pancreatitis. Distinguishing markers from mediators of severe acute pancreatitis (SAP) is important since targeting mediators may improve outcomes. We evaluated potential agents in human pancreatic necrotic collections (NCs), pseudocysts (PCs) and pancreatic cystic neoplasms and used pancreatic acini, peripheral blood mononuclear cells (PBMC) and an acute pancreatitis (AP) model to determine SAP mediators.

METHODS

We measured acinar and PBMC injury induced by agents increased in NCs and PCs. Outcomes of caerulein pancreatitis were studied in lean rats coadministered interleukin (IL)-1β and keratinocyte chemoattractant/growth-regulated oncogene, triolein alone or with the lipase inhibitor orlistat.

RESULTS

NCs had higher fatty acids, IL-8 and IL-1β versus other fluids. Lipolysis of unsaturated triglyceride and resulting unsaturated fatty acids (UFA) oleic and linoleic acids induced necro-apoptosis at less than half the concentration in NCs but other agents did not do so at more than two times these concentrations. Cytokine coadministration resulted in higher pancreatic and lung inflammation than caerulein alone, but only triolein coadministration caused peripancreatic fat stranding, higher cytokines, UFAs, multisystem organ failure (MSOF) and mortality in 97% animals, which were prevented by orlistat.

CONCLUSIONS

UFAs, IL-1β and IL-8 are elevated in NCs. However, UFAs generated via peripancreatic fat lipolysis causes worse inflammation and MSOF, converting mild AP to SAP.

Prediction of the severity of acute pancreatitis on admission by carboxypeptidase-B activation peptide: A systematic review and meta-analysis

OBJECTIVES

The assessment of acute pancreatitis severity on admission currently remains a challenge to clinicians. A single, rapid biochemical marker would be preferable to clinical and radiological scoring systems. The aim of this study was to undertake a meta-analysis on the value of carboxypeptidase-B activation peptide (CAPAP) in predicting severity of acute pancreatitis on admission.

METHODS

Major databases and trial registries were searched to identify all relevant studies from January 1998 to March 2015. Pooled sensitivity, specificity and the diagnostic odds ratios (DOR) with 95% confidence interval (CI) were calculated for each study and were compared to other biomarkers, if included, within the same study. Summary receiver-operating curves (ROC) were conducted and the area under the curve (AUC) was evaluated.

RESULTS

In total, six studies were included. At the time of admission, the AUC of serum CAPAP for predicting severity of acute pancreatitis was 0.86 with pooled sensitivity, specificity and DOR of 0.90, 0.70 and 19.08, respectively. When serum CAPAP was compared with urinary CAPAP, the AUC, pooled sensitivity, specificity and DOR were 0.69 vs 0.88, 0.90 vs 0.81, 0.68 vs. 0.77 and 17.96 vs. 18.58, respectively. Similarly, the AUC, pooled sensitivity, specificity and DOR of serum CAPAP vs maximal serum C-reactive protein within the first 3 days of admission were found to be 0.97 vs. 0.82, 0.92 vs. 0.88, 0.81 vs 0.68 and 37.90 vs. 18.80, respectively.

CONCLUSIONS

Both serum and urinary CAPAP have the potential to act as a stratification marker on admission in predicting severity of acute pancreatitis.

Lipolysis of visceral adipocyte triglyceride by pancreatic lipases converts mild acute pancreatitis to severe pancreatitis independent of necrosis and inflammation

Visceral fat necrosis has been associated with severe acute pancreatitis (SAP) for over 100 years; however, its pathogenesis and role in SAP outcomes are poorly understood. Based on recent work suggesting that pancreatic fat lipolysis plays an important role in SAP, we evaluated the role of pancreatic lipases in SAP-associated visceral fat necrosis, the inflammatory response, local injury, and outcomes of acute pancreatitis (AP). For this, cerulein pancreatitis was induced in lean and obese mice, alone or with the lipase inhibitor orlistat and parameters of AP induction (serum amylase and lipase), fat necrosis, pancreatic necrosis, and multisystem organ failure, and inflammatory response were assessed. Pancreatic lipases were measured in fat necrosis and were overexpressed in 3T3-L1 cells. We noted obesity to convert mild cerulein AP to SAP with greater cytokines, unsaturated fatty acids (UFAs), and multisystem organ failure, and 100% mortality without affecting AP induction or pancreatic necrosis. Increased pancreatic lipase amounts and activity were noted in the extensive visceral fat necrosis of dying obese mice. Lipase inhibition reduced fat necrosis, UFAs, organ failure, and mortality but not the parameters of AP induction. Pancreatic lipase expression increased lipolysis in 3T3-L1 cells. We conclude that UFAs generated via lipolysis of visceral fat by pancreatic lipases convert mild AP to SAP independent of pancreatic necrosis and the inflammatory response.

IL-6 trans-signaling promotes pancreatitis-associated lung injury and lethality

Acute lung injury (ALI) is an inflammatory disease with a high mortality rate. Although typically seen in individuals with sepsis, ALI is also a major complication in severe acute pancreatitis (SAP). The pathophysiology of SAP-associated ALI is poorly understood, but elevated serum levels of IL-6 is a reliable marker for disease severity. Here, we used a mouse model of acute pancreatitis-associated (AP-associated) ALI to determine the role of IL-6 in ALI lethality. Il6-deficient mice had a lower death rate compared with wild-type mice with AP, while mice injected with IL-6 were more likely to develop lethal ALI. We found that inflammation-associated NF-κB induced myeloid cell secretion of IL-6, and the effects of secreted IL-6 were mediated by complexation with soluble IL-6 receptor, a process known as trans-signaling. IL-6 trans-signaling stimulated phosphorylation of STAT3 and production of the neutrophil attractant CXCL1 in pancreatic acinar cells. Examination of human samples revealed expression of IL-6 in combination with soluble IL-6 receptor was a reliable predictor of ALI in SAP. These results demonstrate that IL-6 trans-signaling is an essential mediator of ALI in SAP across species and suggest that therapeutic inhibition of IL-6 may prevent SAP-associated ALI.

Sensing of commensal organisms by the intracellular sensor NOD1 mediates experimental pancreatitis

The intracellular sensor NOD1 has important host-defense functions relating to a variety of pathogens. Here, we showed that this molecule also participates in the induction of a noninfectious pancreatitis via its response to commensal organisms. Pancreatitis induced by high-dose cerulein (a cholecystokinin receptor agonist) administration depends on NOD1 stimulation by gut microflora. To analyze this NOD1 activity, we induced pancreatitis by simultaneous administration of a low dose of cerulein (that does not itself induce pancreatitis) and FK156, an activator of NOD1 that mimics the effect of gut bacteria that have breached the mucosal barrier. The pancreatitis was dependent on acinar cell production of the chemokine MCP-1 and the intrapancreatic influx of CCR2(+) inflammatory cells. Moreover, MCP-1 production involved activation of the transcription factors NF-κB and STAT3, each requiring complementary NOD1 and cerulein signaling. These studies indicate that gut commensals enable noninfectious pancreatic inflammation via NOD1 signaling in pancreatic acinar cells.

Structural and Functional Analysis of the Complex between Citrate and the Zinc Peptidase Carboxypeptidase A

A high-resolution carboxypeptidase-Zn(2+)-citrate complex was studied by X-ray diffraction and enzyme kinetics for the first time. The citrate molecule acts as a competitive inhibitor of this benchmark zinc-dependent peptidase, chelating the catalytic zinc ion in the active site of the enzyme and inducing a conformational change such that carboxypeptidase adopts the conformation expected to occur by substrate binding. Citrate adopts an extended conformation with half of the molecule facing the zinc ion, while the other half is docked in the S1' hydrophobic specificity pocket of the enzyme, in contrast with the binding mode expected for a substrate like phenylalanine or a peptidomimetic inhibitor like benzylsuccinic acid. Combined structural and enzymatic analysis describes the characteristics of the binding of this ligand that, acting against physiologically relevant zinc-dependent proteases, may serve as a general model in the design of new drug-protecting molecules for the oral delivery of drugs of peptide origin.

Pomalidomide suppresses cerulein-induced acute pancreatitis in mice

BACKGROUND

An overproduction of proinflammatory mediators in severe acute pancreatitis contributes to the systemic inflammatory response, which may lead to multiorgan damage and even death. Thus, inflammatory cytokines, e.g., tumor necrosis factor (TNF)-α and interleukin (IL)-1β, may be novel targets for the treatment of acute pancreatitis. The aim of this study was to investigate the therapeutic effects of pomalidomide (or CC-4047), a thalidomide analog and immunomodulatory agent, in acute pancreatitis.

METHODS

Acute pancreatitis was induced in C57BL/6 mice by intraperitoneal administration of cerulein (100 μg/kg/h × 8). Pomalidomide was administered (0.5 mg/kg orally) 1 h before the first or 1 h after the last cerulein administration. The severity of the acute pancreatitis was evaluated biochemically and morphologically.

RESULTS

Pretreatment with pomalidomide significantly reduced the plasma levels of amylase and lipase; the histological injury; and the expression of TNF-α, IL-1β, monocyte chemotactic protein-1 (MCP-1), and inducible nitric oxide synthase (iNOS) in cerulein-induced acute pancreatitis. Post-treatment with pomalidomide also decreased the cerulein-induced elevation of plasma amylase and lipase and decreased the pancreatic damage.

CONCLUSIONS

Treatment with pomalidomide ameliorated the severity of cerulein-induced acute pancreatitis in mice. Our data suggest that pomalidomide may become a new therapeutic agent in future clinical trials for the treatment of acute pancreatitis.

Analysis of a new crystal form of procarboxypeptidase B: further insights into the catalytic mechanism

A new triclinic crystal structure form of porcine pancreatic procarboxypeptidase B (PCPB) was obtained at higher resolution than the previously known tetragonal crystal structure. This new crystal polymorph has allowed for a corrected, accurate assignment of residues along the polypeptide chain based on the currently available gene sequence information and crystallographic data. The present structure shows unbound PCPB in a distinct molecular packing as compared to the previous benzamidine complexed form. Its catalytically important Tyr248 residue is oriented and hydrogen-bonded to solvent water molecules, and locates the furthest away from the catalytic zinc ion as compared to previous structures. A relatively long stretch of residues flanking Tyr248 and guarding the access to the catalytic zinc ion was found to be sequentially unique to the M14 family of peptidases. Predictions from a normal mode analysis indicated that this stretch of residues belongs to a rigid subdomain in the protein structure. The specific presence of a tyrosyl residue at the most exposed position in this region would allow for a delicate balance between extreme hydrophobicity and hydrophilicity, and affect substrate binding and the kinetic efficiency of the enzyme.

Mechanisms of dexamethasone-mediated chemokine down-regulation in mild and severe acute pancreatitis

This study aimed to investigate the role of therapeutic dexamethasone (Dex) treatment on the mechanisms underlying chemokine expression during mild and severe acute pancreatitis (AP) experimentally induced in rats. Regardless of the AP severity, Dex (1 mg/kg), administered 1 h after AP, reduced the acinar cell activation of extracellular signal-regulated kinase (ERK) and c-Jun-NH(2)-terminal kinase (JNK) but failed to reduce p38-mitogen-activated protein kinase (MAPK) in severe AP. In both AP models, Dex inhibited the activation of nuclear factor-kappaB (NF-kappaB) and signal transducers and activators of transcription (STAT) factors. All of this resulted in pancreatic down-regulation of the chemokines monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC). Lower plasma chemokine levels as well as decreased amylasemia, hematocrit and plasma interleukin-1beta (Il-1beta) levels were found either in mild or severe AP treated with Dex. Pancreatic neutrophil infiltration was attenuated by Dex in mild but not in severe AP. In conclusion, by targeting MAPKs, NF-kappaB and STAT3 pathways, Dex treatment down-regulated the chemokine expression in different cell sources during mild and severe AP, resulting in decreased severity of the disease.

Protease activation, pancreatic leakage, and inflammation in acute pancreatitis: differences between mild and severe cases and changes over the first three days

BACKGROUND/AIMS

The pathophysiology of acute pancreatitis (AP) may be studied using markers of protease activation (active carboxypeptidase B (aCAP), the activation peptide of carboxypeptidase B (CAPAP)), leakage of pancreatic enzymes (trypsinogen-2, procarboxypeptidase B (proCAP), amylase), and inflammation (monocyte chemoattractant protein-1 (MCP-1), CRP).

METHODS

This prospective study included 140 cases of AP. Mild (n = 124) and severe (n = 16) cases were compared with respect to serum levels of trypsinogen-2, proCAP, amylase, aCAP, CAPAP (serum/urine), MCP-1 (serum/urine) and CRP on days 1, 2 and 3 from onset of symptoms. All patients with information on all 3 days were included in a time-course analysis (n = 44-55, except amylase: n = 27).

RESULTS

High levels in severe versus mild cases were seen for trypsinogen-2, CAPAP in serum and urine, and MCP-1 in serum on days 1-3. No differences were seen for proCAP, amylase and aCAP. MCP-1 in urine was significantly elevated on day 1-2, and CRP on day 2-3. CAPAP and MCP-1 levels peaked early and stayed elevated for 48 h in serum.

CONCLUSION

Protease activation and inflammation are early events in AP, with high levels of these markers within 24 h. Protease activation declines after 48 h, whereas inflammation is present for a longer time.

Advance in laboratory markers of acute severe pancreatitis

Acute pancreatitis (AP) was one of common acute abdominal diseases in digestive system, and it was divided into mild type and severe type. Many methods were used to judge the severity of AP, including all kinds of scoring system, biochemical indexes, and imaging methods. Recent researches found that some serum indexes such as acute reactive proteins, cytokines, enzymes, active peptides and procalcitonin could classify the severity of AP and judge the risks of complications. This article reviews the progress in the laboratory markers of severe AP.