Acute lipotoxicity regulates severity of biliary acute pancreatitis without affecting its initiation

Prospective observational study and mechanistic evidence showing lipolysis of circulating triglycerides worsens hypertriglyceridemic acute pancreatitis

BACKGROUNDWhile most hypertriglyceridemia is asymptomatic, hypertriglyceridemia-associated acute pancreatitis (HTG-AP) can be more severe than AP of other etiologies. The reasons underlying this are unclear. We thus examined whether lipolytic generation of nonesterified fatty acids (NEFAs) from circulating triglycerides (TGs) could worsen clinical outcomes.METHODSAdmission serum TGs, NEFA composition, and concentrations were analyzed prospectively for 269 patients with AP. These parameters, demographics, and clinical outcomes were compared between HTG-AP (TGs >500 mg/dL; American Heart Association [AHA] 2018 guidelines) and AP of other etiologies. Serum NEFAs were correlated with serum TG fatty acids (TGFAs) alone and with the product of TGFA serum lipase (NEFAs - TGFAs × lipase). Studies in mice and rats were conducted to understand the role of HTG lipolysis in organ failure and to interpret the NEFA-TGFA correlations.RESULTSPatients with HTG-AP had higher serum NEFA and TG levels and more severe AP (19% vs. 7%; P < 0.03) than did individuals with AP of other etiologies. Correlations of long-chain unsaturated NEFAs with corresponding TGFAs increased with TG concentrations up to 500 mg/dL and declined thereafter. However, NEFA - TGFA × lipase correlations became stronger with TGs above 500 mg/dL. AP and intravenous lipase infusion in rodents caused lipolysis of circulating TGs to NEFAs. This led to multisystem organ failure, which was prevented by pancreatic TG lipase deletion or lipase inhibition.CONCLUSIONSHTG-AP is made severe by the NEFAs generated from intravascular lipolysis of circulating TGs. Strategies that prevent TG lipolysis may be effective in improving clinical outcomes for patients with HTG-AP.FUNDINGNational Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, NIH) (RO1DK092460 and R01DK119646); Department of Defense (PR191945 under W81XWH-20-1-0400); National Institute on Alcohol Abuse and Alcoholism (NIAAA), NIH (R01AA031257).

Visceral adipose tissue predicts severity and prognosis of acute pancreatitis in obese patients

Acute pancreatitis is a common systemic inflammatory disease, manifested by a spectrum of severity, ranging from mild in the majority of patients to severe acute pancreatitis. Patients with severe acute pancreatitis suffer from severe local and systemic complications and organ failure, leading to a poor prognosis. The early recognition of the severe condition is important to improve prognosis. Obesity has risen in tandem with an increase in the severity of acute pancreatitis in recent years. Studies have revealed that adipose tissue, particularly visceral adipose tissue is associated with the prognosis of acute pancreatitis. This review discussed the role of visceral adipose tissue in obese patients with acute pancreatitis and explored the possible mechanism involved.

Research Progress on the Mechanism of Acute Hypertriglyceridemic Pancreatitis

ABSTRACT

The incidence rate of hypertriglyceridemia pancreatitis (HTGP) has experienced a notable increase in recent years, with eclipsing alcohol as the second leading cause of acute pancreatitis (AP). HTGP is often associated with more severe local and systemic complications. Recognized as a metabolic disorder hypertriglyceridemia (HTG), it holds significant relevance in the pathogenesis of HTGP, yet its mechanisms are not fully understood. Both primary (genetic) and secondary (acquired) factors contribute to elevated triglyceride (TG) levels, which concurrently influence the progression of HTGP. This article presents a comprehensive review of the evolving research on HTGP pathogenesis, encompassing lipid synthesis and metabolism, calcium signal transduction, inflammatory mediators, endoplasmic reticulum stress, autophagy, mitochondrial injury by fatty acids, oxidative stress response, genetic factors, and gene mutations. By unraveling the intricate mechanisms underlying HTGP, this article aims to enhance physicians' understanding of the disease and facilitate the development of potential targeted pharmacological interventions for patients.

Adipose Triglyceride Lipase-Mediated Adipocyte Lipolysis Exacerbates Acute Pancreatitis Severity in Mouse Models and Patients

Dyslipolysis of adipocytes plays a critical role in various diseases. Adipose triglyceride lipase (ATGL) is a rate-limiting enzyme in adipocyte autonomous lipolysis. However, the degree of adipocyte lipolysis related to the prognoses in acute pancreatitis (AP) and the role of ATGL-mediated lipolysis in the pathogenesis of AP remain elusive. Herein, the visceral adipose tissue consumption rate in the acute stage was measured in both patients with AP and mouse models. Lipolysis levels and ATGL expression were detected in cerulein-induced AP models. CL316,243, a lipolysis stimulator, and adipose tissue-specific ATGL knockout mice were used to further investigate the role of lipolysis in AP. The ATGL-specific inhibitor, atglistatin, was used in C57Bl/6N and ob/ob AP models. This study indicated that increased visceral adipose tissue consumption rate in the acute phase was independently associated with adverse prognoses in patients with AP, which was validated in mouse AP models. Lipolysis of adipocytes was elevated in AP mice. Stimulation of lipolysis aggravated AP. Genetic blockage of ATGL specifically in adipocytes alleviated the damage to AP. The application of atglistatin effectively protected against AP in both lean and obese mice. These findings demonstrated that ATGL-mediated adipocyte lipolysis exacerbates AP and highlighted the therapeutic potential of ATGL as a drug target for AP.

Buprenorphine affects the initiation and severity of interleukin-induced acute pancreatitis in mice

Acute pancreatitis (AP) is a common disease with no targeted therapy and has varied outcomes ranging from spontaneous resolution to being lethal. Although typically painful, AP can also be painless. Various agents, including opioids, are used for pain control in AP; the risks and benefits of which are often debated. As experimental AP in mice is used to study the efficacy of potential therapies, we studied the effect of a commonly used opioid, buprenorphine, on the initiation and progression of AP. For this, we administered extended-release buprenorphine subcutaneously before inducing the previously established severe AP model that uses interleukins 12 and 18 (IL12,18) in genetically obese (ob/ob) mice and compared this to mice with AP but without the drug. Mice were monitored over 3 days, and parameters of AP induction and progression were compared. Buprenorphine significantly reduced serum amylase, lipase, pancreatic necrosis, and AP-associated fat necrosis, which is ubiquitous in obese mice and humans. Buprenorphine delayed the AP-associated reduction of carotid artery pulse distention and the development of hypothermia, hastened renal injury, and muted the early increase in respiratory rate versus IL12,18 alone. The site of buprenorphine injection appeared erythematous, inflamed, and microscopically showed thinning, loss of epidermal layers that had increased apoptosis. In summary, subcutaneous extended-release buprenorphine interfered with the induction of AP by reducing serum amylase, lipase, pancreatic and fat necrosis, the worsening of AP by delaying hypotension, hypothermia, while hastening renal injury, respiratory depression, and causing cutaneous injury at the site of injection.NEW & NOTEWORTHY Extended-release buprenorphine interferes with the initiation and progression of acute pancreatitis at multiple levels.

Association between serum triglyceride level and severity of acute biliary pancreatitis

BACKGROUND

Acute biliary pancreatitis (ABP) is the most common type of acute pancreatitis. However, the effect of serum triglyceride (TG) levels on the severity of ABP remains unclear. The aim of this study was to assess the correlation between serum TG levels and the severity of ABP.

METHODS

Data from 526 ABP patients was analyzed in this study. The patients were divided into normal and elevated groups according to the TG level measured within 24 h after admission, and the elevated group was further divided into mild, moderate, and severe elevated groups. The demographic data and clinical outcomes of each group were compared.

RESULTS

Of the 526 ABP patients, 394 were in the normal TG group and 132 were in the elevated TG group (36 mild, 57 moderate, and 39 severe). The elevated group was younger (51.5 ± 12.9 vs. 58.9 ± 13.9), predominantly male (66.7% vs. 45.2%), had more history of diabetes (22.7% vs. 12.4%) and hyperlipidemia (19.7% vs. 0.8%), and developed systemic inflammatory response syndrome (SIRS) (25.8% vs. 15.5%), persistent organ failure (POF) (11.4% vs. 2.8%), and local complications (62.9% vs. 42.1%) more frequently compared to the normal group (P < 0.05). The incidence of SIRS, POF, acute peripancreatic fluid collection (APFC), and acute necrotic collection (ANC) increased with increasing TG levels (Ptrend < 0.05). In multivariate analysis, TG was independently associated with POF, APFC, and ANC in increments of 100 mg/dl (P < 0.05), and there was a linear relationship between TG levels and POF, APFC, and ANC (non-linear P > 0.05, P overall <0.05). In addition, nonalcoholic fatty liver disease is not a risk factor for POF, ANC, and APFC in ABP patients.

CONCLUSIONS

Elevated serum TG levels were independently associated with more severe ABP. The incidence of POF, APFC, and ANC in ABP patients increased with the increase of TG levels, with a linear relationship.

Synthesis of 2,4-Dicyanoalkylated Benzoxazines through the Radical-Mediated Cascade Cyclization of Isocyanides with AIBN under Metal- and Additive-Free Conditions

A general and novel method for the radical cascade cyclization of aryl isocyanides with AIBN has been described. This strategy provides straightforward access to various 2,4-dicyanoalkylated benzoxazines in moderate to good yields under metal- and additive-free conditions. The reaction can apply to a gram scale and tolerate diverse functional groups. 2,4-Dicyanoalkylated benzoxazine derivatives feature a large Stokes shift and intramolecular charge transfer properties.

NSAIDs do not reduce severity among post-ERCP pancreatitis patients

OBJECTIVE

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most studied chemoprophylaxis for post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP). While previous systematic reviews have shown NSAIDs reduce PEP, their impact on moderate to severe PEP (MSPEP) is unclear. We conducted a systematic review and meta-analysis to understand the impact of NSAIDs on MSPEP among patients who developed PEP. We later surveyed physicians' understanding of that impact.

DESIGN

A systematic search for randomized trials using NSAIDs for PEP prevention was conducted. Pooled-prevalence and Odds-ratio of PEP, MSPEP were compared between treated vs. control groups. Analysis was performed using R software. Random-effects model was used for all variables. Physicians were surveyed via email before and after reviewing our results.

RESULTS

7688 patients in 25 trials were included. PEP was significantly reduced to 0.598 (95%CI, 0.47-0.76) in the NSAIDs group. Overall burden of MSPEP was reduced among all patients undergoing ERCP: OR 0.59 (95%CI, 0.42-0.83). However, NSAIDs didn't affect the proportion of MSPEP among those who developed PEP (p = 0.658). Rectal Indomethacin and diclofenac reduced PEP but not MSPEP. Efficacy didn't vary by risk, timing of administration, or bias-risk. Survey revealed a change in the impression of the effect of NSAIDs on MSPEP after reviewing our results.

CONCLUSIONS

Rectal diclofenac or indomethacin before or after ERCP reduce the overall burden of MSPEP by reducing the pool of PEP from which it can arise. However, the proportion of MSPEP among patients who developed PEP is unaffected. Therefore, NSAIDs prevent initiation of PEP, but do not affect severity among those that develop PEP. Alternative modalities are needed to reduce MSPEP among patients who develop PEP.

Understanding Hypertriglyceridemia: Integrating Genetic Insights

Hypertriglyceridemia is an exceptionally complex metabolic disorder characterized by elevated plasma triglycerides associated with an increased risk of acute pancreatitis and cardiovascular diseases such as coronary artery disease. Its phenotype expression is widely heterogeneous and heavily influenced by conditions as obesity, alcohol consumption, or metabolic syndromes. Looking into the genetic underpinnings of hypertriglyceridemia, this review focuses on the genetic variants in LPL, APOA5, APOC2, GPIHBP1 and LMF1 triglyceride-regulating genes reportedly associated with abnormal genetic transcription and the translation of proteins participating in triglyceride-rich lipoprotein metabolism. Hypertriglyceridemia resulting from such genetic abnormalities can be categorized as monogenic or polygenic. Monogenic hypertriglyceridemia, also known as familial chylomicronemia syndrome, is caused by homozygous or compound heterozygous pathogenic variants in the five canonical genes. Polygenic hypertriglyceridemia, also known as multifactorial chylomicronemia syndrome in extreme cases of hypertriglyceridemia, is caused by heterozygous pathogenic genetic variants with variable penetrance affecting the canonical genes, and a set of common non-pathogenic genetic variants (polymorphisms, using the former nomenclature) with well-established association with elevated triglyceride levels. We further address recent progress in triglyceride-lowering treatments. Understanding the genetic basis of hypertriglyceridemia opens new translational opportunities in the scope of genetic screening and the development of novel therapies.

A single-center experience of non-bioartificial DFAPP support systems among Chinese patients with hyperlipidemic moderate/severe acute pancreatitis

To assess the clinical efficacy of Double Filtration Plasmapheresis (DFAPP), a novel blood purification method, in treating hyperlipidemic moderate/severe pancreatitis (HL-M/SAP). A total of 68 HL-M/SAP patients were enrolled in this study. The observation group, comprising 34 patients, received DFAPP treatment, while the control group underwent CVVH + PA treatment. We compared the efficacy changes between the two groups post-treatment. Patients treated with DFAPP showed significant improvements in clinical outcomes. After 72 h of DFAPP treatment, HL-M/SAP patients exhibited notably lower multiple organ failure scores and a reduced mortality rate compared to those in the CVVH + PA group. Triglyceride levels in HL-M/SAP patients treated with DFAPP for 48 h averaged 3.75 ± 1.95, significantly lower than the 9.57 ± 3.84 levels in the CVVH + PA group (P < 0.05). Moreover, CRP levels decreased markedly, IL-17 levels diminished, IL-10 levels increased, and the decline in IL-35 levels was significantly less pronounced compared to the CVVH + PA group. The recurrence rate of pancreatitis was also significantly lower after 6 months. The early implementation of DFAPP in HL-M/SAP patients effectively reduces triglyceride levels, suppresses pro-inflammatory factors, enhances anti-inflammatory factors, and mitigates cytokine storm-induced sepsis damage. Consequently, this leads to a decrease in the incidence of multiple organ failure, improved patient survival rates, and a reduce the recurrence rate of lipogenic pancreatitis.Trial registration: Chinese Clinical Trial Registry, ChiCTR2300076066.

Amphipathic Liponecrosis Impairs Bacterial Clearance and Causes Infection During Sterile Inflammation

BACKGROUND & AIMS

Although transient bacteremia is common during dental and endoscopic procedures, infections developing during sterile diseases like acute pancreatitis (AP) can have grave consequences. We examined how impaired bacterial clearance may cause this transition.

METHODS

Blood samples from patients with AP, normal controls, and rodents with pancreatitis or those administered different nonesterified fatty acids (NEFAs) were analyzed for albumin-unbound NEFAs, microbiome, and inflammatory cell injury. Macrophage uptake of unbound NEFAs using a novel coumarin tracer were done and the downstream effects-NEFA-membrane phospholipid (phosphatidylcholine) interactions-were studied on isothermal titration calorimetry.

RESULTS

Patients with infected AP had higher circulating unsaturated NEFAs; unbound NEFAs, including linoleic acid (LA) and oleic acid (OA); higher bacterial 16S DNA; mitochondrial DNA; altered β-diversity; enrichment in Pseudomonadales; and increased annexin V-positive myeloid (CD14) and CD3-positive T cells on admission. These, and increased circulating dead inflammatory cells, were also noted in rodents with unbound, unsaturated NEFAs. Isothermal titration calorimetry showed progressively stronger unbound LA interactions with aqueous media, phosphatidylcholine, cardiolipin, and albumin. Unbound NEFAs were taken into protein-free membranes, cells, and mitochondria, inducing voltage-dependent anion channel oligomerization, reducing ATP, and impairing phagocytosis. These were reversed by albumin. In vivo, unbound LA and OA increased bacterial loads and impaired phagocytosis, causing infection. LA and OA were more potent for these amphipathic interactions than the hydrophobic palmitic acid.

CONCLUSIONS

Release of stored LA and OA can increase their circulating unbound levels and cause amphipathic liponecrosis of immune cells via uptake by membrane phospholipids. This impairs bacterial clearance and causes infection during sterile inflammation.

Relationship of circulating levels of long-chain fatty acids to persistent organ failure in acute pancreatitis

During acute pancreatitis (AP), free fatty acids (FFAs) are liberated from circulating triglycerides (TG) and injured adipocytes by pancreatic lipase. Circulating FFAs have been suspected as a source of systemic lipotoxicity in AP. However, assessment of FFAs is difficult and time-consuming, and little is known about relative levels of FFAs between patients with different severities of AP and controls. This study's aims were to assess early circulating levels of FFAs, (both saturated and unsaturated) in patients with AP vs. controls, and associations between FFA levels and AP severity. Serum samples from patients with AP were collected at enrollment (day 1 of hospital stay); serum samples were also collected from controls. FFAs including palmitic, palmitoleic, stearic, oleic, and linoleic acid were extracted and quantitated using gas chromatography separation. Severity of AP was determined by Revised Atlanta Classification. Differences in FFA levels and percentages of total FFAs were assessed between patients with AP and controls and patients with AP of different severity grades. A total of 93 patients with AP (48 female, 52%) and 29 controls (20 female, 69%) were enrolled. Of the patients with AP, 74 had mild/moderate and 19 had severe AP. Serum levels of all FFAs except stearic acid were significantly higher in patients with AP compared with controls. A strong and independent association between elevated palmitoleic acid levels and severe AP was found. Serum unsaturated FFA levels, specifically palmitoleic acid, appear to correlate with severe AP. These findings have potential clinical implications for targeted AP therapies.NEW & NOTEWORTHY Drivers of the inflammatory response in acute pancreatitis remain incompletely understood. Unsaturated fatty acids, specifically palmitoleic, appear to have an association with more severe acute pancreatitis. This finding presents a new clinical understanding of fatty acid toxicity and highlights a potential future target for treatment in severe acute pancreatitis.

Intrapancreatic fat, pancreatitis, and pancreatic cancer

Pancreatic cancer is typically detected at an advanced stage, and is refractory to most forms of treatment, contributing to poor survival outcomes. The incidence of pancreatic cancer is gradually increasing, linked to an aging population and increasing rates of obesity and pancreatitis, which are risk factors for this cancer. Sources of risk include adipokine signaling from fat cells throughout the body, elevated levels of intrapancreatic intrapancreatic adipocytes (IPAs), inflammatory signals arising from pancreas-infiltrating immune cells and a fibrotic environment induced by recurring cycles of pancreatic obstruction and acinar cell lysis. Once cancers become established, reorganization of pancreatic tissue typically excludes IPAs from the tumor microenvironment, which instead consists of cancer cells embedded in a specialized microenvironment derived from cancer-associated fibroblasts (CAFs). While cancer cell interactions with CAFs and immune cells have been the topic of much investigation, mechanistic studies of the source and function of IPAs in the pre-cancerous niche are much less developed. Intriguingly, an extensive review of studies addressing the accumulation and activity of IPAs in the pancreas reveals that unexpectedly diverse group of factors cause replacement of acinar tissue with IPAs, particularly in the mouse models that are essential tools for research into pancreatic cancer. Genes implicated in regulation of IPA accumulation include KRAS, MYC, TGF-β, periostin, HNF1, and regulators of ductal ciliation and ER stress, among others. These findings emphasize the importance of studying pancreas-damaging factors in the pre-cancerous environment, and have significant implications for the interpretation of data from mouse models for pancreatic cancer.

Fatty change of the pancreas: the Pandora's box of pancreatology

Prevention of common diseases of the pancreas or interception of their progression is as attractive in theory as it is elusive in practice. The fundamental challenge has been an incomplete understanding of targets coupled with a multitude of intertwined factors that are associated with the development of pancreatic diseases. Evidence over the past decade has shown unique morphological features, distinctive biomarkers, and complex relationships of intrapancreatic fat deposition. Fatty change of the pancreas has also been shown to affect at least 16% of the global population. This knowledge has solidified the pivotal role of fatty change of the pancreas in acute pancreatitis, chronic pancreatitis, pancreatic cancer, and diabetes. The pancreatic diseases originating from intrapancreatic fat (PANDORA) hypothesis advanced in this Personal View cuts across traditional disciplinary boundaries with a view to tackling these diseases. New holistic understanding of pancreatic diseases is well positioned to propel pancreatology through lasting research breakthroughs and clinical advances.

Inflammation of Mesenteric Adipose Tissue Correlates with Intestinal Injury and Disease Severity in Rats with Severe Acute Pancreatitis

BACKGROUND

Visceral adipose tissue (VAT) is related to SAP prognosis. As a depot of VAT, mesenteric adipose tissue (MAT) resides between pancreas and gut, which might affect SAP and the secondary intestinal injury.

AIMS

To investigate the changes of MAT in SAP.

METHODS

24 SD rats were randomly divided into four groups. 18 rats in SAP group were euthanized in time gradients (6 h, 24 h, and 48 h after modeling) and the others in control group. Blood samples and tissues of pancreas, gut, and MAT were taken for analysis.

RESULTS

Compared to the control group, SAP rats appeared MAT inflammation, presenting higher mRNA expression of TNF-α and IL-6 and lower IL-10, and histological changes after 6 h of modeling, which became worse over time. Flow cytometry showed that B lymphocytes increased in MAT after 24 h of SAP modeling and lasted up to 48 h, earlier than the changes of T lymphocytes and macrophages. The intestinal barrier integrity was damaged after 6 h of modeling, presenting lower mRNA and protein expression of ZO-1 and occludin, higher serum levels of LPS and DAO, with pathological changes, which gradually aggravated after 24 h and 48 h. SAP rats had higher serum levels of inflammatory indicators and revealed histological inflammation of pancreas, the severity of which increased with the passage of modeling time.

CONCLUSION

MAT appeared inflammation in early-stage SAP, and became worse over time, with the same trend as the intestinal barrier injury and the severity of pancreatitis. B lymphocytes infiltrated early in MAT, which might promote the MAT inflammation.

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.

Pancreatic changes with lifestyle and age: What is normal and what is concerning?

During the aging process, typical morphological changes occur in the pancreas, which leads to a specific "patchy lobular fibrosis in the elderly." The aging process in the pancreas is associated with changes in volume, dimensions, contour, and increasing intrapancreatic fat deposition. Typical changes are seen in ultrasonography, computed tomography, endosonography, and magnetic resonance imaging. Typical age-related changes must be distinguished from lifestyle-related changes. Obesity, high body mass index, and metabolic syndrome also lead to fatty infiltration of the pancreas. In the present article, age-related changes in morphology and imaging are discussed. Particular attention is given to the sonographic verification of fatty infiltration of the pancreas. Ultrasonography is a widely used screening examination method. It is important to acknowledge the features of the normal aging processes and not to interpret them as pathological findings. Reference is made to the uneven fatty infiltration of the pancreas. The differential diagnostic and the differentiation from other processes and diseases leading to fatty infiltration of the pancreas are discussed.

Impact of sex and comorbid diabetes on hospitalization outcomes in acute pancreatitis: A large United States population-based study

BACKGROUNDS

Data on the association between comorbid diabetes mellitus (DM) and acute pancreatitis (AP) remains limited. Utilizing a large, nationwide database, we aimed to examine the impact of comorbid diabetes mellitus on patients admitted for acute pancreatitis.

METHODS

This was a retrospective case-control study of adult patients with AP utilizing the National Inpatient Sample from 2015-2018, using ICD-10 codes. Hospitalization outcomes of patients admitted for AP with comorbid DM were compared to those without comorbid DM at the time of admission. The primary outcome was a mortality difference between the cohorts. Multivariable-adjusted cox proportional hazards model analysis was performed. Data was analyzed as both sex aggregated, and sex segregated.

RESULTS

940,789 adult patients with AP were included, of which 256,330 (27.3%) had comorbid DM. Comorbid DM was associated with a 31% increased risk of inpatient mortality (aOR: 1.31; p = 0.004), a 53% increased risk of developing sepsis (aOR: 1.53; p = 0.002), increased hospital length of stay (LOS) (4.5 days vs. 3.7 days; p < 0.001), and hospital costs ($9934 vs. $8486; p < 0.001). Whites admitted for AP with comorbid DM were at a 49% increased risk of mortality as compared to Hispanics (aOR: 1.49; p < 0.0001). Different comorbidities had sex-specific risks; men admitted for AP with comorbid DM were at a 28% increased risk of mortality (aOR: 1.28; p < 0.0001) as compared to women. Men with comorbid DM plus obesity or hypertension were also at increased risk of mortality as compared to women, whereas women with comorbid DM plus renal failure were at greater risk of mortality as compared to men.

CONCLUSIONS

Comorbid DM appears to be a risk factor for adverse hospitalization outcomes in patients admitted for AP with male sex and race as additional risk factors. Future prospective studies are warranted to confirm these findings to better risk stratify this patient population.

Evidence showing lipotoxicity worsens outcomes in covid-19 patients and insights about the underlying mechanisms

We compared three hospitalized patient cohorts and conducted mechanistic studies to determine if lipotoxicity worsens COVID-19. Cohort-1 (n = 30) compared COVID-19 patients dismissed home to those requiring intensive-care unit (ICU) transfer. Cohort-2 (n = 116) compared critically ill ICU patients with and without COVID-19. Cohort-3 (n = 3969) studied hypoalbuminemia and hypocalcemia’s impact on COVID-19 mortality. Patients requiring ICU transfer had higher serum albumin unbound linoleic acid (LA). Unbound fatty acids and LA were elevated in ICU transfers, COVID-19 ICU patients and ICU non-survivors. COVID-19 ICU patients (cohort-2) had greater serum lipase, damage-associated molecular patterns (DAMPs), cytokines, hypocalcemia, hypoalbuminemia, organ failure and thrombotic events. Hypocalcemia and hypoalbuminemia independently associated with COVID-19 mortality in cohort-3. Experimentally, LA reacted with albumin, calcium and induced hypocalcemia, hypoalbuminemia in mice. Endothelial cells took up unbound LA, which depolarized their mitochondria. In mice, unbound LA increased DAMPs, cytokines, causing endothelial injury, organ failure and thrombosis. Therefore, excessive unbound LA in the circulation may worsen COVID-19 outcomes.

•

Three cohorts of hospitalized COVID-19 patients with different severities were studied

•

Severe COVID-19 increased serum linoleic acid (LA) and unbound fatty acid levels

•

Endothelial cell uptake of unbound LA dose-dependently depolarized mitochondria

•

Unbound LA increased cytokines, endothelial injury, organ failure and thrombosis

Doppler-Guided Acoustically Active Injection Catheter: Transendocardial Delivery Assessed by an Efficacy Testing Animal Model

Percutaneous transendocardial injections of therapeutic agents into the myocardium may not always be effective. We used an animal model for assessing the efficacy of the injections using linoleic acid as a testing agent. Efficacious delivery into the myocardium of a beating heart was indicated by rapidly developed local myocardial necrosis and wall motion abnormalities using echocardiography. We employed this experimental model to test our innovative technology, an acoustically active injection catheter. The Doppler ultrasound-guided acoustically active injection catheter effectively delivers the substance to the myocardium but needs further technical improvements to minimize an unwanted systemic distribution of the agent.

Impact of pancreatic fat on the risk of post-endoscopic retrograde cholangiopancreatography pancreatitis

BACKGROUND AND STUDY AIMS

Fatty pancreas is a potential risk factor for acute pancreatitis; however, whether it is also a risk factor for post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) has not been evaluated. We aimed to determine the impact of fatty pancreas on the development of PEP.

METHODS

We analyzed the data of patients who underwent abdominal computed tomography (CT) scan and sequential therapeutic endoscopic retrograde cholangiopancreatography (ERCP). Fatty change in the pancreas was evaluated based on pancreatic attenuation of unenhanced image on CT scan. The risk of fatty pancreas for the development of PEP was evaluated using a logistic regression model.

RESULTS

Of a total of 858 patients included in the study, 354 (41.3%) had fatty pancreas, while 504 (58.7%) did not have fatty pancreas. PEP developed in 28 patients (7.9%) in the fatty pancreas group and in 13 patients (2.6%) in the no fatty pancreas group. Fatty pancreas was significantly associated with the development of PEP (odds ratio [OR] [95% confidence interval [CI]] 2.38 [1.16-4.87]). A history of acute pancreatitis, female sex, difficult cannulation, and endoscopic papillary balloon dilation were also risk factors for the development of PEP. The risk for moderate-to-severe PEP development tended to be higher in the fatty pancreas group than in the no fatty pancreas group (OR [95% CI] 5.61 [0.63-49.62]).

CONCLUSIONS

Fatty pancreas is a significant risk factor for the development of PEP. Clinicians need to be aware of the risk of fatty pancreas for the development of PEP prior to performing ERCP.

Magnetic Resonance Imaging-Based Radiomics Models to Predict Early Extrapancreatic Necrosis in Acute Pancreatitis

OBJECTIVE

The aim of the study was to investigate radiomics models based on magnetic resonance imaging (MRI) for predicting early extrapancreatic necrosis (EXPN) in acute pancreatitis.

METHODS

Radiomics features were extracted from T2-weighted images of extrapancreatic collections and late arterial-phase images of the pancreatic parenchyma for 135 enrolled patients (94 in the primary cohort, including 47 EXPN patients and 41 in the validation cohort, including 20 EXPN patients). The optimal features after dimension reduction were used for radiomics modeling through a support vector machine. A clinical model, the MR severity index score, and extrapancreatic inflammation on MRI were evaluated.

RESULTS

Twelve optimal features from the extrapancreatic collection images and 10 from the pancreatic parenchyma images were selected for modeling. The pancreatic parenchyma-based and extrapancreatic collection-based radiomics models showed good predictive accuracy in both the training and validation cohorts. The areas under the curve of the extrapancreatic collection-based radiomics model (0.969 and 0.976) were consistent with those of the pancreatic parenchyma-based model (0.931 and 0.921) for both cohorts and better than those of the clinical model and imaging scores for both cohorts.

CONCLUSIONS

The MRI-based radiomics models of both the extrapancreatic collections and the pancreatic parenchyma had excellent predictive performance for early EXPN.

Pathophysiology and Biomarker Potential of Fatty Acid Ethyl Ester Elevation During Alcoholic Pancreatitis

BACKGROUND & AIMS

The role of fatty acid ethyl esters (FAEEs) during human alcoholic pancreatitis is unknown. We compared FAEEs levels with their nonesterified fatty acids (NEFAs) precursors during alcohol intoxication and clinical alcoholic pancreatitis. The pathophysiology underlying FAEEs increase and their role as diagnostic biomarkers for alcoholic pancreatitis was investigated.

METHODS

A prospective blinded study compared FAEEs, NEFAs, and ethanol blood levels on hospitalization for alcoholic pancreatitis (n = 31), alcohol intoxication (n = 25), and in normal controls (n = 43). Serum FAEEs were measured at admission for nonalcoholic pancreatitis (n = 75). Mechanistic cell and animal studies were done.

RESULTS

Median FAEEs were similarly elevated during alcohol intoxication (205 nmol/L; 95% confidence interval [CI], 71.8-515 nmol/L, P < .001) and alcoholic pancreatitis (103.1 nmol/L; 95% CI, 53-689 nmol/L, P < .001) vs controls (1.7 nmol/L; 95% CI, 0.02-4.3 nmol/L) or nonalcoholic pancreatitis (8 nmol/L; 95% CI, 1.1-11.5 nmol/L). Alcoholic pancreatitis increased serum NEFAs (1024 ± 710 μmol/L vs 307 ± 185 μmol/L in controls, P < .05). FAEEs comprised 0.1% to 2% of the parent NEFA concentrations. FAEES correlated strongly with NEFAs independent of ethanol levels in alcoholic pancreatitis but not during alcohol intoxication. On receiver operating characteristic curve analysis for diagnosing alcoholic pancreatitis, the area under the curve for serum FAEEs was 0.87 (95% CI, 0.78-0.95, P < .001). In mice and cells, alcohol administration transiently increased all FAEEs. Oleic acid ethyl ester was the only FAEE with a sustained increase up to 24 hours after intraperitoneal oleic acid plus ethanol administration.

CONCLUSIONS

The sustained, alcohol-independent, large (20- to 50-fold) increase in circulating FAEEs during alcoholic pancreatitis results from their visceral release and mirrors the 2- to 4-fold increase in parent NEFA. The large areas under the curve of FAEEs on receiver operating characteristic curve analysis supports their role as alcoholic pancreatitis biomarkers.

Post-pancreatitis diabetes mellitus and excess intra-pancreatic fat deposition as harbingers of pancreatic cancer

Progress in the fight against pancreatic cancer has been hampered by many factors. One of them is the inability to detect the disease early in overwhelming majority of patients. The present paper outlines a novel way in which progress could be accelerated. This includes a focus on two harbingers—post-pancreatitis diabetes mellitus and excess intra-pancreatic fat deposition—that converge at affecting the tumor macroenvironment and microenvironment specifically in the pancreas, not other organs. The two entities have the potential to be incorporated into future screening strategies with a view to early detecting of pancreatic cancer.

Sex Differences in the Exocrine Pancreas and Associated Diseases

Differences in pancreatic anatomy, size, and function exist in men and women. The anatomical differences could contribute to the increase in complications associated with pancreatic surgery in women. Although diagnostic criteria for pancreatitis are the same in men and women, major sex differences in etiology are reported. Alcohol and tobacco predominate in men, whereas idiopathic and obstructive etiologies predominate in women. Circulating levels of estrogens, progesterone, and androgens contribute significantly to overall health outcomes; premenopausal women have lower prevalence of cardiovascular and pancreatic diseases suggesting protective effects of estrogens, whereas androgens promote growth of normal and cancerous cells. Sex chromosomes and gonadal and nongonadal hormones together determine an individual's sex, which is distinct from gender or gender identity. Human pancreatic disease etiology, outcomes, and sex-specific mechanisms are largely unknown. In rodents of both sexes, glucocorticoids and estrogens from the adrenal glands influence pancreatic secretion and acinar cell zymogen granule numbers. Lack of corticotropin-releasing factor receptor 2 function, a G protein-coupled receptor whose expression is regulated by both estrogens and glucocorticoids, causes sex-specific changes in pancreatic histopathology, zymogen granule numbers, and endoplasmic reticulum ultrastructure changes in acute pancreatitis model. Here, we review existing literature on sex differences in the normal exocrine pancreas and mechanisms that operate at homeostasis and diseased states in both sexes. Finally, we review pregnancy-related pancreatic diseases and discuss the effects of sex differences on proposed treatments in pancreatic disease.

Pancreatic triglyceride lipase mediates lipotoxic systemic inflammation

Visceral adipose tissue plays a critical role in numerous diseases. Although imaging studies often show adipose involvement in abdominal diseases, their outcomes may vary from being a mild self-limited illness to one with systemic inflammation and organ failure. We therefore compared the pattern of visceral adipose injury during acute pancreatitis and acute diverticulitis to determine its role in organ failure. Acute pancreatitis-associated adipose tissue had ongoing lipolysis in the absence of adipocyte triglyceride lipase (ATGL). Pancreatic lipase injected into mouse visceral adipose tissue hydrolyzed adipose triglyceride and generated excess nonesterified fatty acids (NEFAs), which caused organ failure in the absence of acute pancreatitis. Pancreatic triglyceride lipase (PNLIP) increased in adipose tissue during pancreatitis and entered adipocytes by multiple mechanisms, hydrolyzing adipose triglyceride and generating excess NEFAs. During pancreatitis, obese PNLIP-knockout mice, unlike obese adipocyte-specific ATGL knockouts, had lower visceral adipose tissue lipolysis, milder inflammation, less severe organ failure, and improved survival. PNLIP-knockout mice, unlike ATGL knockouts, were protected from adipocyte-induced pancreatic acinar injury without affecting NEFA signaling or acute pancreatitis induction. Therefore, during pancreatitis, unlike diverticulitis, PNLIP leaking into visceral adipose tissue can cause excessive visceral adipose tissue lipolysis independently of adipocyte-autonomous ATGL, and thereby worsen organ failure.

The Effects of Rhein and Honokiol on Metabolic Profiles in a Mouse Model of Acute Pancreatitis

BACKGROUND Acute pancreatitis (AP) is generally a self-limiting inflammatory disease, but is associated with a high mortality rate when severe. The present study aimed to investigate the effects of rhein and honokiol on AP. MATERIAL AND METHODS Thirty mice were randomly divided into 5 groups (n=6 per group): blank control, AP model, AP+rhein, AP+honokiol, and AP+rhein+honokiol. The AP model was prepared by intraperitoneal injection of cerulein and lipopolysaccharide (LPS). We observed the pathological changes of the pancreas by hematoxylin and eosin (H&E) staining. A mouse amylase kit was utilized to detect the level of amylase content in serum. Gas chromatography mass spectrometer analysis was performed to detect the differences in metabolites among the blank control, AP model, and AP+rhein+honokiol groups. RESULTS The serum amylase level was significantly higher in the AP model, which suggested that the AP model was constructed successfully. The AP+rhein+honokiol group had significantly reduced interstitial edema, inflammatory cell infiltration, hemorrhage, and necrosis. In addition, the rhein and honokiol treatment influenced some of the metabolic pathways in AP, including riboflavin metabolism, glycerophospholipid metabolism, linoleic acid metabolism, and the pentose and glucuronate interconversions pathway. CONCLUSIONS This study showed that the combination of rhein and honokiol ameliorated pathological changes in the pancreas of mice with AP.

Dietary Fat Patterns and Outcomes in Acute Pancreatitis in Spain

Background/Objective: Evidence from basic and clinical studies suggests that unsaturated fatty acids (UFAs) might be relevant mediators of the development of complications in acute pancreatitis (AP). Objective: The aim of this study was to analyze outcomes in patients with AP from regions in Spain with different patterns of dietary fat intake.

Materials and Methods: A retrospective analysis was performed with data from 1,655 patients with AP from a Spanish prospective cohort study and regional nutritional data from a Spanish cross-sectional study. Nutritional data considered in the study concern the total lipid consumption, detailing total saturated fatty acids, UFAs and monounsaturated fatty acids (MUFAs) consumption derived from regional data and not from the patient prospective cohort. Two multivariable analysis models were used: (1) a model with the Charlson comorbidity index, sex, alcoholic etiology, and recurrent AP; (2) a model that included these variables plus obesity.

Results: In multivariable analysis, patients from regions with high UFA intake had a significantly increased frequency of local complications, persistent organ failure (POF), mortality, and moderate-to-severe disease in the model without obesity and a higher frequency of POF in the model with obesity. Patients from regions with high MUFA intake had significantly more local complications and moderate-to-severe disease; this significance remained for moderate-to-severe disease when obesity was added to the model.

Conclusions: Differences in dietary fat patterns could be associated with different outcomes in AP, and dietary fat patterns may be a pre-morbid factor that determines the severity of AP. UFAs, and particulary MUFAs, may influence the pathogenesis of the severity of AP.

Ringer's Lactate Prevents Early Organ Failure by Providing Extracellular Calcium

OBJECTIVE

Ringer's lactate may improve early systemic inflammation during critical illnesses like severe acute pancreatitis, which are associated with hypocalcemia. Ringer's lactate is buffered and contains lactate and calcium. We, thus analyzed extracellular calcium or lactate's effects on the mechanisms, intermediary markers, and organ failure in models mimicking human disease with nonesterified fatty acid (NEFA) elevation.

METHODS

Meta-analyses and experimental studies were performed. Experimentally, extracellular calcium and lactate were compared in their interaction with linoleic acid (LA; a NEFA increased in human severe pancreatitis), and its subsequent effects on mitochondrial depolarization and cytosolic calcium signaling resulting in cell injury. In vivo, the effect of LA was studied on organ failure, along with the effect of calcium or lactate (pH 7.4) on severe acute pancreatitis-associated organ failure. A meta-analysis of human randomized control trials comparing Ringer's lactate to normal saline was done, focusing on necrosis and organ failure.

RESULTS

Calcium reacted ionically with LA and reduced lipotoxic necrosis. In vivo, LA induced organ failure and hypocalcemia. During severe pancreatitis, calcium supplementation in saline pH 7.4, unlike lactate, prevented hypocalcemia, increased NEFA saponification, reduced circulating NEFA and C-reactive protein , reduced pancreatic necrosis adjacent to fat necrosis, and normalized shock (carotid pulse distension) and blood urea nitrogen elevation on day 1. This, however, did not prevent the later increase in serum NEFA which caused delayed organ failure. Meta-analysis showed Ringer's lactate reduced necrosis, but not organ failure, compared with normal saline.

CONCLUSION

Hypocalcemia occurs due to excess NEFA binding calcium during a critical illness. Ringer's lactate's early benefits in systemic inflammation are by the calcium it provides reacting ionically with NEFA. This, however, does not prevent later organ failure from sustained NEFA generation. Future studies comparing calcium supplemented saline resuscitation to Ringer's lactate may provide insights to this pathophysiology.

Ca2+ Influx Channel Inhibitor SARAF Protects Mice From Acute Pancreatitis

BACKGROUND & AIMS

Pancreatitis is characterized by increased influx of Ca²⁺ into acinar cells, by unknown mechanisms. Inhibitors of Ca²⁺ influx channels could be effective in treating acute pancreatitis, but these have deleterious side effects that can result in death. We investigated the expression patterns and functions of acinar cell Ca²⁺ channels and factors that regulate them during development of acute pancreatitis, along with changes in the channel inactivator store-operated calcium entry-associated regulatory factor (SARAF). We investigated whether SARAF is a target for treatment of acute pancreatitis and its status in human with pancreatitis.

METHODS

We generated mice that expressed SARAF tagged with hemagglutinin, using CRISPR/Cas9 gene editing, and isolated acinar cells. We also performed studies with Saraf^-/- mice, Saraf^zf/zf mice, mice without disruption of Saraf (control mice), and mice that overexpress fluorescently labeled SARAF in acinar cells. We analyzed interactions between stromal interaction molecule 1 (STIM1) and SARAF in HEK cells stimulated with carbachol using fluorescence resonance energy transfer microscopy and immunoprecipitation. Mice were given injections of caerulein or L-arginine to induce pancreatitis. Pancreatic tissues and blood samples were collected and levels of serum amylase, trypsin, tissue damage, inflammatory mediators, and inflammatory cells were measured. We performed quantitative polymerase chain reaction analyses of pancreatic tissues from 6 organ donors without pancreatic disease (controls) and 8 patients with alcohol-associated pancreatitis.

RESULTS

Pancreatic levels of Ca²⁺ influx channels or STIM1 did not differ significantly between acinar cells from mice with vs. without pancreatitis. By contrast, pancreatic levels of Saraf messenger RNA and SARAF protein initially markedly increased but then decreased during cell stimulation or injection of mice with caerulein, resulting in excessive Ca²⁺ influx. STIM1 interacted stably with SARAF following stimulation of HEK or mouse acinar cells with physiologic levels of carbachol, but only transiently following stimulation with pathologic levels of carbachol, leading to excessive Ca²⁺ influx. We observed reduced levels of SARAF messenger RNA in pancreatic tissues from patients with pancreatitis, compared with controls. SARAF knockout mice developed more severe pancreatitis than control mice after administration of caerulein or L-arginine, and pancreatic acinar cells from these mice had significant increases in Ca²⁺ influx. Conversely, overexpression of SARAF in acini reduced Ca²⁺ influx, eliminated inflammation, and reduced severity of acute pancreatitis.

CONCLUSIONS

In mice with pancreatitis, SARAF initially increases but is then degraded, resulting in excessive, pathological Ca²⁺ influx by acinar cells. SARAF knockout mice develop more severe pancreatitis than control mice, whereas mice that express SARAF from a transgene in acinar cells develop less-severe pancreatitis. SARAF therefore appears to prevent pancreatic damage during development of acute pancreatitis. Strategies to stabilize or restore SARAF to acinar cells might be developed for treatment of pancreatitis.

Large triglyceride-rich lipoproteins in hypertriglyceridemia are associated with the severity of acute pancreatitis in experimental mice

Hypertriglyceridemia severity is linked to acute pancreatitis prognosis, but it remains unknown why a portion of severe hypertriglyceridemia patients do not develop severe acute pancreatitis. To investigate whether hypertriglyceridemia subtypes affect acute pancreatitis progression, we analyzed two genetically modified hypertriglyceridemia mouse models—namely, glycosylphosphatidylinositol high-density lipoprotein binding protein 1 knockout (Gpihbp1−/−) and apolipoprotein C3 transgenic (ApoC3-tg) mice. Acute pancreatitis was induced by 10 intraperitoneal caerulein injections. Biochemical assays and pathological analysis were performed for the severity evaluation of acute pancreatitis. Plasma triglyceride-rich lipoproteins (TRLs), including chylomicrons and very low-density lipoprotein (VLDL), were collected via ultracentrifugation to evaluate their cytotoxic effects on primary pancreatic acinar cells (PACs). We found that the particle sizes of Gpihbp1−/− TRLs were larger than ApoC3-tg TRLs. Severe pancreatic injury with large areas of pancreatic necrosis in the entire lobule was induced in Gpihbp1−/− mice when plasma triglyceride levels were greater than 2000 mg/dL. However, ApoC3-tg mice with the same triglyceride levels did not develop large areas of pancreatic necrosis, even upon the administration of poloxamer 407 to further increase triglyceride levels. Meanwhile, in the acute pancreatitis model, free fatty acids (FFAs) in the pancreas of Gpihbp1−/− mice were greater than in ApoC3-tg mice. TRLs from Gpihbp1−/− mice released more FFAs and were more toxic to PACs than those from ApoC3-tg mice. Chylomicrons from patients showed the same effects on PACs as TRLs from Gpihbp1−/− mice. Gpihbp1−/− mice with triglyceride levels below 2000 mg/dL had milder pancreatic injury and less incidence of pancreatic necrosis than those with triglyceride levels above 2000 mg/dL, similar to Gpihbp1−/−mice with triglyceride levels above 2000 mg/dL but with fenofibrate administration. These findings demonstrated that hypertriglyceridemia subtypes with large TRL particles could affect acute pancreatitis progression and that chylomicrons showed more cytotoxicity than VLDL by releasing more FFAs.

New insights into acute pancreatitis

The incidence of acute pancreatitis continues to increase worldwide, and it is one of the most common gastrointestinal causes for hospital admission in the USA. In the past decade, substantial advancements have been made in our understanding of the pathophysiological mechanisms of acute pancreatitis. Studies have elucidated mechanisms of calcium-mediated acinar cell injury and death and the importance of store-operated calcium entry channels and mitochondrial permeability transition pores. The cytoprotective role of the unfolded protein response and autophagy in preventing sustained endoplasmic reticulum stress, apoptosis and necrosis has also been characterized, as has the central role of unsaturated fatty acids in causing pancreatic organ failure. Characterization of these pathways has led to the identification of potential molecular targets for future therapeutic trials. At the patient level, two classification systems have been developed to classify the severity of acute pancreatitis into prognostically meaningful groups, and several landmark clinical trials have informed management strategies in areas of nutritional support and interventions for infected pancreatic necrosis that have resulted in important changes to acute pancreatitis management paradigms. In this Review, we provide a summary of recent advances in acute pancreatitis with a special emphasis on pathophysiological mechanisms and clinical management of the disorder.

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.

Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis

Acute lipolysis of visceral fat or circulating triglycerides may worsen acute pancreatitis (AP)-associated local and systemic injury. The pancreas expresses pancreatic triacylglycerol lipase (PNLIP), pancreatic lipase-related protein 2 (PNLIPRP2), and carboxyl ester lipase (CEL), which may leak into the visceral fat or systemic circulation during pancreatitis. We, thus, aimed to determine the pancreatic lipase(s) regulating lipotoxicity during AP. For this AP, associated fat necrosis was analyzed using Western blot analysis. Bile acid (using liquid chromatography-tandem mass spectrometry) and fatty acid (using gas chromatography) concentrations were measured in human fat necrosis. The fat necrosis milieu was simulated in vitro using glyceryl trilinoleate because linoleic acid is increased in fat necrosis. Bile acid requirements to effectively hydrolyze glyceryl trilinoleate were studied using exogenous or overexpressed lipases. The renal cell line (HEK 293) was used to study lipotoxic injury. Because dual pancreatic lipase knockouts are lethal, exocrine parotid acini lacking lipases were used to verify the results. PNLIP, PNLIPRP2, and CEL were increased in fat necrosis. Although PNLIP and PNLIPRP2 were equipotent in inducing lipolysis and lipotoxic injury, CEL required bile acid concentrations higher than in human fat necrosis. The high bile acid requirements for effective lipolysis make CEL an unlikely mediator of lipotoxic injury in AP. It remains to be explored whether PNLIP or PNLIPRP2 worsens AP severity in vivo.

Multimodal Transgastric Local Pancreatic Hypothermia Reduces Severity of Acute Pancreatitis in Rats and Increases Survival

BACKGROUND & AIMS

Acute pancreatitis (AP) of different etiologies is associated with the activation of different signaling pathways in pancreatic cells, posing challenges to the development of targeted therapies. We investigated whether local pancreatic hypothermia, without systemic hypothermia, could lessen the severity of AP induced by different methods in rats.

METHODS

A urethane balloon with 2 polyurethane tubes was placed inside the stomach of rats. AP was induced in Wistar rats by the administration of cerulein or glyceryl tri-linoleate (GTL). Then, cold water was infused into the balloon to cool the pancreas. Pancreatic temperatures were selected based on those found to decrease acinar cell injury. An un-perfused balloon was used as a control. Pancreatic and rectal temperatures were monitored, and an infrared lamp or heating pad was used to avoid generalized hypothermia. We collected blood, pancreas, kidney, and lung tissues and analyzed them by histology, immunofluorescence, immunoblot, cytokine and chemokine magnetic bead, and DNA damage assays. The effect of hypothermia on signaling pathways initiated by cerulein and GTL was studied in acinar cells.

RESULTS

Rats with pancreatic cooling developed less severe GTL-induced AP compared with rats that received the control balloon. In acinar cells, cooling decreased the lipolysis induced by GTL, increased the micellar form of its fatty acid, lowered the increase in cytosolic calcium, prevented the loss of mitochondrial membrane potential (by 70%-80%), and resulted in a 40%-50% decrease in the uptake of a fatty acid tracer. In rats with AP, cooling decreased pancreatic necrosis by 48%, decreased serum levels of cytokines and markers of cell damage, and decreased markers of lung and renal damage. Pancreatic cooling increased the proportions of rats surviving 6 hours after induction of AP (to 90%, from <10% of rats that received the control balloon). In rats with cerulein-induced AP, pancreatic cooling decreased pancreatic markers of apoptosis and inflammation.

CONCLUSIONS

In rats with AP, transgastric local pancreatic hypothermia decreases pancreatic necrosis, apoptosis, inflammation, and markers of pancreatitis severity and increases survival.

The effect of serum triglyceride concentration on the outcome of acute pancreatitis: systematic review and meta-analysis

Elevated serum triglyceride concentration (seTG, >1.7 mM or >150 mg/dL) or in other words hypertriglyceridemia (HTG) is common in the populations of developed countries. This condition is accompanied by an increased risk for various diseases, such as acute pancreatitis (AP). It has been proposed that HTG could also worsen the course of AP. Therefore, in this meta-analysis, we aimed to compare the effects of various seTGs on the severity, mortality, local and systemic complications of AP, and on intensive care unit admission. 16 eligible studies, including 11,965 patients were retrieved from PubMed and Embase. The results showed that HTG significantly elevated the odds ratio (OR = 1.72) for severe AP when compared to patients with normal seTG (<1.7 mM). Furthermore, a significantly higher occurrence of pancreatic necrosis, persistent organ failure and renal failure was observed in groups with HTG. The rates of complications and mortality for AP were significantly increased in patients with seTG >5.6 mM or >11.3 mM versus <5.6 mM or <11.3 mM, respectively. We conclude that the presence of HTG worsens the course and outcome of AP, but we found no significant difference in AP severity based on the extent of HTG.

Role of obesity in the release of extracellular nucleosomes in acute pancreatitis: a clinical and experimental study

BACKGROUND/OBJECTIVES

A high body mass index increases the risk of severe pancreatitis and associated mortality. Our aims were: (1) To determine whether obesity affects the release of extracellular nucleosomes in patients with pancreatitis; (2) To determine whether pancreatic ascites confers lipotoxicity and triggers the release of extracellular nucleosomes in lean and obese rats.

METHODS

DNA and nucleosomes were determined in plasma from patients with mild or moderately severe acute pancreatitis either with normal or high body mass index (BMI). Lipids from pancreatic ascites from lean and obese rats were analyzed and the associated toxicity measured in vitro in RAW 264.7 macrophages. The inflammatory response, extracellular DNA and nucleosomes were determined in lean or obese rats with pancreatitis after peritoneal lavage.

RESULTS

Nucleosome levels in plasma from obese patients with mild pancreatitis were higher than in normal BMI patients; these levels markedly increased in obese patients with moderately severe pancreatitis vs. those with normal BMI. Ascites from obese rats exhibited high levels of palmitic, oleic, stearic, and arachidonic acids. Necrosis and histone 4 citrullination-marker of extracellular traps-increased in macrophages incubated with ascites from obese rats but not with ascites from lean rats. Peritoneal lavage abrogated the increase in DNA and nucleosomes in plasma from lean or obese rats with pancreatitis. It prevented fat necrosis and induction of HIF-related genes in lung.

CONCLUSIONS

Extracellular nucleosomes are intensely released in obese patients with acute pancreatitis. Pancreatitis-associated ascitic fluid triggers the release of extracellular nucleosomes in rats with severe pancreatitis.

Stereochemical Structure Activity Relationship Studies (S-SAR) of Tetrahydrolipstatin

Tetrahydrolipstatin (THL), its enantiomer, and an additional six diastereomers were evaluated as inhibitors of the hydrolysis of p-nitrophenyl butyrate by porcine pancreatic lipase. IC₅₀s were found for all eight stereoisomers ranging from a low of 4.0 nM for THL to a high of 930 nM for the diastereomer with the inverted stereocenters at the 2,3,2'-positions. While the enantiomer of THL was also significantly less active (77 nM) the remaining five stereoisomers retained significant inhibitory activities (IC₅₀s = 8.0 to 20 nM). All eight compounds were also evaluated against three human cancer cell lines (human breast cancers MCF-7 and MDA-MB-231, human large-cell lung carcinoma H460). No appreciable cytotoxicity was observed for THL and its seven diastereomers, as their IC₅₀s in a MTT cytotoxicity assay were all greater than 3 orders of magnitude of camptothecin.

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-8 gene polymorphism in acute biliary and non biliary pancreatitis: probable cause of high level parameters?

Backgrounds/Aims

Inflammatory mediators of the innate immune response play fundamental roles in the pathogenesis of acute pancreatitis. The correlation between interleukin-8 (IL-8) gene polymorphism with types of acute pancreatitis and severity of pancreatitis, was evaluated in this study.

Methods

According to the diagnostic criteria, 176 patients with acute pancreatitis were grouped into biliary (n=83) and nonbiliary pancreatitis (n=93). Healthy blood donors (n=100) served as controls. Serum alanine transaminase, aspartate transaminase, total and direct bilirubin, amylase, lypase, white blood cell count and c-reactive protein levels were evaluated to correlate with IL-8 rs4073 (-251T/A) polymorphism, which was analyzed using a real-time polymerase chain reaction method with melting point analysis.

Results

The IL-8 AA genotype was detected with a significantly higher frequency among the patients with acute biliary pancreatitis having higher alanine transaminase levels than the median range. Homozygote alleles were significantly higher among patients with acute biliary pancreatitis having amylase levels higher than the median range.

Conclusions

Determination of the frequency of IL-8 polymorphism in acute pancreatitis is informative and provides further evidence concerning the role of IL-8 in laboratory tests.

Palmitic acid aggravates inflammation of pancreatic acinar cells by enhancing unfolded protein response induced CCAAT-enhancer-binding protein β-CCAAT-enhancer-binding protein α activation

Hypertriglyceridemia is an independent risk factor for acute pancreatitis, in which the pathological mechanisms are not fully illustrated. Intracellular inflammatory response is a key pathological response in acute pancreatitis and endoplasmic reticulum stress has been suggested to induce inflammation and CCAAT-enhancer-binding protein expression. Therefore, the current study aims to elucidate the possible relationship between endoplasmic reticulum stress and inflammation in hypertriglyceridemia associated pancreatitis and the possible involvement of CCAAT-enhancer-binding protein. In cholecystokinin-8 stimulated rat primary acinar cells, incubation with palmitic acid caused the activation of endoplasmic reticulum stress and inflammatory responses. Pre-incubation with the chemical chaperone 4-phenylbutyric acid inhibited inflammatory responses induced by palmitic acid, whereas stimulation with the endoplasmic reticulum stress inducer thapsigargin alone induced inflammatory responses. Meanwhile we found that the transcription factors CCAAT-enhancer-binding protein α and CCAAT-enhancer-binding protein β were also induced in the palmitic acid-stimulated pancreatic acinar cells, and were similarly inhibited by 4-phenylbutyric acid pre-incubation and induced by thapsigargin stimulation alone, indicating that endoplasmic reticulum stress was responsible for CCAAT-enhancer-binding protein α and CCAAT-enhancer-binding protein β induction in the pancreatic acinar cells. Knockdown of CCAAT-enhancer-binding protein β by siRNA transfection inhibited inflammatory responses and CCAAT-enhancer-binding protein α induction but did not affect endoplasmic reticulum stress. Our study provides strong evidence that in response to palmitic acid stimulation, endoplasmic reticulum stress induces inflammatory responses in pancreatic acinar cells through induction of the CCAAT-enhancer-binding protein family, wherein CCAAT-enhancer-binding protein β activation is responsible for CCAAT-enhancer-binding protein α activation.

Outcome benefit of abdominal paracentesis drainage for severe acute pancreatitis patients with serum triglyceride elevation by decreasing serum lipid metabolites

BACKGROUND

Our previous reports demonstrated that abdominal paracentesis drainage (APD) exerts a beneficial effect on severe acute pancreatitis (SAP) patients. However, the underlying mechanisms for this effectiveness are not well understood.

METHODS

A retrospective cohort of 132 consecutive non-hypertriglyceridemia (HTG)-induced SAP patients with triglyceride (TG) elevation and pancreatitis-associated ascitic fluid (PAAF) was recruited from May 2010 to May 2015 and included in this study. The patients were divided into two groups: the APD group (n = 68) and the non-APD group (n = 64). The monitored parameters mainly included mortality, hospital stay, the incidence of further intervention, levels of serum lipid metabolites and inflammatory factors, parameters related to organ failure and infections, and severity scores.

RESULTS

The demographic data and severity scores were comparable between the two groups. Compared with the non-APD group, the primary outcomes (including mortality, hospital stay and the incidence of percutaneous catheter drainage) in the APD group were improved. The serum levels of lipid metabolites were significantly lower in the APD group after 2 weeks of treatment than in the non-APD group. Logistic regression analysis indicated that the decreased extent of free fatty acid (FFA)(odds ratio, 1.435; P = 0.015) was a predictor of clinical improvement after 2 weeks of treatment.

CONCLUSION

Treatment with APD benefits non-HTG-induced SAP patients with serum TG elevation by decreasing serum levels of FFA.

Characterization and Predictive Value of Near Infrared 2-Deoxyglucose Optical Imaging in Severe Acute Pancreatitis

Background

Studying the uptake of 2-deoxy glucose (2-DG) analogs such as 2-Deoxy-2-[18F] fluoroglucose (FDG) is a common approach to identify and monitor malignancies and more recently chronic inflammation. While pancreatitis is a common cause for false positive results in human studies on pancreatic cancer using FDG, the relevance of these findings to acute pancreatitis (AP) is unknown. FDG has a short half-life. Thus, with an aim to accurately characterize the metabolic demand of the pancreas during AP in real-time, we studied the uptake of the non-radioactive, near infrared fluorescence labelled 2-deoxyglucose analog, IRDye^® 800CW 2-DG probe (NIR 2-DG; Li-Cor) during mild and severe biliary AP.

Methods

Wistar rats (300 g; 8–12/group) were administered NIR 2-DG (10 nM; I.V.). Mild and severe biliary AP were respectively induced by biliopancreatic duct ligation (DL) alone or along with infusing glyceryl trilinoleate (GTL; 50 μL/100 g) within 10 minutes of giving NIR 2-DG. Controls (CON) only received NIR 2-DG. Imaging was done every 5–10 minutes over 3 hrs. Average Radiant Efficiency [p/s/cm²/sr]/[μW/cm²] was measured over the pancreas using the IVIS 200 in-vivo imaging system (PerkinElmer) using the Living Image^® software and verified in ex vivo pancreata. Blood amylase, lipase and pancreatic edema, necrosis were measured over the course of AP.

Results

NIR 2-DG uptake over the first hour was not influenced by AP induction. However, while the signal declined in controls and rats with mild AP, there was significantly higher retention of NIR 2-DG in the pancreas after 1 hour in those with GTL pancreatitis. The increase was > 3 fold over controls in the GTL group and was verified to be in the pancreas ex vivo. In vitro, pancreatic acini exposed to GTL had a similar increase in NIR 2-DG uptake which was followed by progressively worse acinar necrosis. Greater retention of NIR 2-DG in vivo was associated with worse pancreatic necrosis, reduced ATP concentrations and mortality, which were not predicted by the blood parameters.

Conclusion

In-vivo fluorescent imaging of a non-radioactive near infrared 2-DG optical probe can predict the AP severity early during the disease.

Fatty Acid Ethyl Esters Are Less Toxic Than Their Parent Fatty Acids Generated during Acute Pancreatitis

Although ethanol causes acute pancreatitis (AP) and lipolytic fatty acid (FA) generation worsens AP, the contribution of ethanol metabolites of FAs, ie, FA ethyl esters (FAEEs), to AP outcomes is unclear. Previously, pancreata of dying alcoholics and pancreatic necrosis in severe AP, respectively, showed high FAEEs and FAs, with oleic acid (OA) and its ethyl esters being the most abundant. We thus compared the toxicities of FAEEs and their parent FAs in severe AP. Pancreatic acini and peripheral blood mononuclear cells were exposed to FAs or FAEEs in vitro. The triglyceride of OA (i.e., glyceryl tri-oleate) or OAEE was injected into the pancreatic ducts of rats, and local and systemic severities were studied. Unsaturated FAs at equimolar concentrations to FAEEs induced a larger increase in cytosolic calcium, mitochondrial depolarization, and necro-apoptotic cell death. Glyceryl tri-oleate but not OAEE resulted in 70% mortality with increased serum OA, a severe inflammatory response, worse pancreatic necrosis, and multisystem organ failure. Our data show that FAs are more likely to worsen AP than FAEEs. Our observations correlate well with the high pancreatic FAEE concentrations in alcoholics without pancreatitis and high FA concentrations in pancreatic necrosis. Thus, conversion of FAs to FAEE may ameliorate AP in alcoholics.

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.

Exposure to Radiocontrast Agents Induces Pancreatic Inflammation by Activation of Nuclear Factor-κB, Calcium Signaling, and Calcineurin

BACKGROUND & AIMS

Radiocontrast agents are required for radiographic procedures, but these agents can injure tissues by unknown mechanisms. We investigated whether exposure of pancreatic tissues to radiocontrast agents during endoscopic retrograde cholangiopancreatography (ERCP) causes pancreatic inflammation, and studied the effects of these agents on human cell lines and in mice.

METHODS

We exposed mouse and human acinar cells to the radiocontrast agent iohexol (Omnipaque; GE Healthcare, Princeton, NJ) and measured intracellular release of Ca(2+), calcineurin activation (using a luciferase reporter), activation of nuclear factor-κB (NF-κB, using a luciferase reporter), and cell necrosis (via propidium iodide uptake). We infused the radiocontrast agent into the pancreatic ducts of wild-type mice (C57BL/6) to create a mouse model of post-ERCP pancreatitis; some mice were given intraperitoneal injections of the calcineurin inhibitor FK506 before and after infusion of the radiocontrast agent. CnAβ(-/-) mice also were used. This experiment also was performed in mice given infusions of adeno-associated virus 6-NF-κB-luciferase, to assess activation of this transcription factor in vivo.

RESULTS

Incubation of mouse and human acinar cells, but not HEK293 or COS7 cells, with iohexol led to a peak and then plateau in Ca(2+) signaling, along with activation of the transcription factors NF-κB and nuclear factor of activated T cells. Suppressing Ca(2+) signaling or calcineurin with BAPTA, cyclosporine A, or FK506 prevented activation of NF-κB and acinar cell injury. Calcineurin Aβ-deficient mice were protected against induction of pancreatic inflammation by iohexol. The calcineurin inhibitor FK506 prevented contrast-induced activation of NF-κB in pancreata of mice, this was observed by live imaging of mice given infusions of adeno-associated virus 6-NF-κB-luciferase.

CONCLUSIONS

Radiocontrast agents cause pancreatic inflammation in mice, via activation of NF-κB, Ca(2+) signaling, and calcineurin. Calcineurin inhibitors might be developed to prevent post-ERCP pancreatitis in patients.

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.

Role of pancreatic fat in the outcomes of pancreatitis

The role of obesity in relation to various disease processes is being increasingly studied, with reports over the last several years increasingly mentioning its association with worse outcomes in acute disease. Obesity has also gained recognition as a risk factor for severe acute pancreatitis (SAP).The mortality in SAP may be as high as 30% and is usually attributable to multi system organ failure (MSOF) earlier in the disease, and complications of necrotizing pancreatitis later [9-11]. To date there is no specific treatment for acute pancreatitis (AP) and the management is largely expectant and supportive. Obesity in general has also been associated with poor outcomes in sepsis and other pathological states including trauma and burns. With the role of unsaturated fatty acids (UFA) as propagators in SAP having recently come to light and with the recognition of acute lipotoxicity, there is now an opportunity to explore different strategies to reduce the mortality and morbidity in SAP and potentially other disease states associated with such a pathophysiology. In this review we will discuss the role of fat and implications of the consequent acute lipotoxicity on the outcomes of acute pancreatitis in lean and obese states and during acute on chronic pancreatitis.