Rosiglitazone improves survival and hastens recovery from pancreatic inflammation in obese mice

The global perspective on peroxisome proliferator-activated receptor γ (PPARγ) in ectopic fat deposition: A review

Excessive expansion of adipocytes can have unhealthy consequences as excess free fatty acids enter other tissues and cause ectopic fat deposition by resynthesizing triglycerides. This lipid accumulation in various tissues is harmful and can increase the risk of related metabolic diseases such as type II diabetes, cardiovascular disease, and insulin resistance. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that play a key role in energy metabolism as fatty acid metabolism sensors, and peroxisome proliferator-activated receptor γ (PPARγ) is the main subtype responsible for fat cell differentiation and adipogenesis. In this paper, we introduce the main structure and function of PPARγ and its regulatory role in the process of lipogenesis in the liver, kidney, skeletal muscle, and pancreas. This information can serve as a reference for further understanding the regulatory mechanisms and measures of the PPAR family in the process of ectopic fat deposition.

Increased lipid metabolism impairs NK cell function and mediates adaptation to the lymphoma environment

Natural killer (NK) cells play critical roles in protection against hematological malignancies but can acquire a dysfunctional state, which limits antitumor immunity. However, the underlying reasons for this impaired NK cell function remain to be uncovered. We found that NK cells in aggressive B-cell lymphoma underwent substantial transcriptional reprogramming associated with increased lipid metabolism, including elevated expression of the transcriptional regulator peroxisome activator receptor-γ (PPAR-γ). Exposure to fatty acids in the lymphoma environment potently suppressed NK cell effector response and cellular metabolism. NK cells from both diffuse large B-cell lymphoma patients and Eµ-myc B-cell lymphoma-bearing mice displayed reduced interferon-γ (IFN-γ) production. Activation of PPAR-γ partially restored mitochondrial membrane potential and IFN-γ production. Overall, our data indicate that increased lipid metabolism, while impairing their function, is a functional adaptation of NK cells to the fatty-acid rich lymphoma environment.

Chromogranin A and its fragments in cardiovascular, immunometabolic, and cancer regulation

Chromogranin A (CgA)-the index member of the chromogranin/secretogranin secretory protein family-is ubiquitously distributed in endocrine, neuroendocrine, and immune cells. Elevated levels of CgA-related polypeptides, consisting of full-length molecules and fragments, are detected in the blood of patients suffering from neuroendocrine tumors, heart failure, renal failure, hypertension, rheumatoid arthritis, and inflammatory bowel disease. Full-length CgA and various CgA-derived peptides, including vasostatin-1, pancreastatin, catestatin, and serpinin, are expressed at different relative levels in normal and pathological conditions and exert diverse, and sometime opposite, biological functions. For example, CgA is overexpressed in genetic hypertension, whereas catestatin is diminished. In rodents, the administration of catestatin decreases hypertension, cardiac contractility, obesity, atherosclerosis, and inflammation, and it improves insulin sensitivity. By contrast, pancreastatin is elevated in diabetic patients, and the administration of this peptide to obese mice decreases insulin sensitivity and increases inflammation. CgA and the N-terminal fragment of vasostatin-1 can enhance the endothelial barrier function, exert antiangiogenic effects, and inhibit tumor growth in animal models, whereas CgA fragments lacking the CgA C-terminal region promote angiogenesis and tumor growth. Overall, the CgA system, consisting of full-length CgA and its fragments, is emerging as an important and complex player in cardiovascular, immunometabolic, and cancer regulation.

Treatment with incretins does not increase the risk of pancreatic diseases compared to older anti-hyperglycaemic drugs, when added to metformin: real world evidence in people with Type 2 diabetes

AIMS

In people with metformin-treated diabetes, to evaluate the risk of acute pancreatitis, pancreatic cancer and other diseases of the pancreas post second-line anti-hyperglycaemic agent initiation.

METHODS

People with Type 2 diabetes diagnosed after 2004 who received metformin plus a dipeptidyl peptidase-4 inhibitor (DPP-4i, n = 50 095), glucagon-like peptide-1 receptor agonist (GLP-1RA, n = 12 654), sulfonylurea (n = 110 747), thiazolidinedione (n = 17 597) or insulin (n = 34 805) for at least 3 months were identified in the US Centricity Electronic Medical Records. Time to developing acute pancreatitis, other diseases of the pancreas and pancreatic cancer was estimated, balancing and adjusting anti-hyperglycaemic drug groups for appropriate confounders.

RESULTS

In the DPP-4i group, the adjusted mean time to acute pancreatitis was 2.63 [95% confidence intervals (CI) 2.38, 2.88] years; time to pancreatic cancer was 2.70 (2.19, 3.21) years; and time to other diseases of the pancreas was 2.73 (2.33, 3.12) years. Compared with DPP-4i, the insulin group developed acute pancreatitis 0.48 years (P < 0.01) earlier and the GLP-1RA group developed pancreatic cancer 3 years later (P < 0.01). However, with the constraint of no event within 6 months of insulin initiation, the risk of acute pancreatitis in the insulin group was insignificant. No other significant differences were observed between groups.

CONCLUSIONS

No significant differences in the risk of developing pancreatic diseases in those treated with various anti-hyperglycaemic drug classes were found.

Incidence, Admission Rates, and Predictors, and Economic Burden of Adult Emergency Visits for Acute Pancreatitis: Data From the National Emergency Department Sample, 2006 to 2012

INTRODUCTION

Acute pancreatitis (AP) is the most common gastroenterology-related reason for hospital admission, and a major source of morbidity and mortality in the United States. This study examines the National Emergency Database Sample, a large national database, to analyze trends in emergency department (ED) utilization and costs, risk factors for hospital admission, and associated hospital costs and length of stay (LOS) in patients presenting with AP.

METHODS

The National Emergency Database Sample (2006 to 2012) was evaluated for trends in ED visits, ED charges, hospitalization rates, hospital charges, and hospital LOS in patients with primary diagnosis of AP (further subcategorized by age and etiology). A survey logistic-regression model was used to determine factors predictive of hospitalization.

RESULTS

A total of 2,193,830 ED visits were analyzed. There was a nonsignificant 5.5% (P=0.07) increase in incidence of ED visits for AP per 10,000 US adults from 2006 to 2012, largely driven by significant increases in ED visits for AP in the 18 to <45 age group (+9.2%; P=0.025), AP associated with alcohol (+15.9%; P=0.001), and AP associated with chronic pancreatitis (+59.5%; P=0.002). Visits for patients aged ≥65 decreased over the time period. Rates of admission and LOS decreased during the time period, while ED and inpatient costs increased (62.1%; P<0.001 and 7.9%; P=0.0011, respectively). Multiple factors were associated with increased risk of hospital admission from the ED, with the strongest predictors being morbid alcohol use [odds ratio (OR), 4.53; P<0.0001], advanced age (age>84 OR, 3.52; P<0.0001), and smoking (OR, 1.75; P<0.0001).

CONCLUSIONS

Despite a relative stabilization in the overall incidence of ED visits for AP, continued increases in ED visits and associated costs appear to be driven by younger patients with alcohol-associated and acute on chronic pancreatitis. While rates of hospitalization and LOS are decreasing, associated inflation-adjusted costs are rising. In addition, identified risk factors for hospitalization, such as obesity, alcohol use, and increased age, should be explored in further study for potential use in predictive models and clinical improvement projects.

Inhibiting role of rosiglitazone in the regulation of inflammatory response and protective effects for severe acute pancreatitis in mice

OBJECTIVES

Our study aimed to probe the effects of rosiglitazone treatment on a severe acute pancreatitis (SAP) model induced by caerulein and investigate the underlying mechanism.

METHODS

Differentially expressed messenger RNAs (mRNAs) in the mice of a SAP group were screened out by microarray analysis. The inflammatory response pathway was obtained from the online website DAVID Bioinformatics Resources 6.8. The interactions of caerulein and its target proteins were shown by search tool for interactions of chemicals (STITCH). Functional interactions of the genes associated with pancreatitis and the target proteins of caerulein were obtained with search tool for interactions of chemicals (STRING). SAP mice were established by hourly intraperitoneal injection of caerulein. Rosiglitazone was used as treatment drug, and pancreatic inflammation was assessed. The expression of Socs3 was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. The expression of interleukin (IL)-6, IL-1b, and Egr1 were studied by RT-PCR and Western blot analysis.

RESULTS

The GSE77983 data were analyzed, and the results showed that Socs3 was overexpressed in SAP tissues. The inflammation response pathway in pancreas was selected by DAVID, STITCH, and STRING. After injection of rosiglitazone in mice, the serum levels of amylase and lipase were decreased. Furthermore, the mRNA and protein levels of Socs3 and inflammatory cytokines in pancreatic tissues were downregulated.

CONCLUSIONS

Rosiglitazone could protect mice with SAP from injury by downregulating Socs3 and inhibiting the inflammatory response pathway.

Chromogranin A Regulation of Obesity and Peripheral Insulin Sensitivity

Chromogranin A (CgA) is a prohormone and granulogenic factor in endocrine and neuroendocrine tissues, as well as in neurons, and has a regulated secretory pathway. The intracellular functions of CgA include the initiation and regulation of dense-core granule biogenesis and sequestration of hormones in neuroendocrine cells. This protein is co-stored and co-released with secreted hormones. The extracellular functions of CgA include the generation of bioactive peptides, such as pancreastatin (PST), vasostatin, WE14, catestatin (CST), and serpinin. CgA knockout mice (Chga-KO) display: (i) hypertension with increased plasma catecholamines, (ii) obesity, (iii) improved hepatic insulin sensitivity, and (iv) muscle insulin resistance. These findings suggest that individual CgA-derived peptides may regulate different physiological functions. Indeed, additional studies have revealed that the pro-inflammatory PST influences insulin sensitivity and glucose tolerance, whereas CST alleviates adiposity and hypertension. This review will focus on the different metabolic roles of PST and CST peptides in insulin-sensitive and insulin-resistant models, and their potential use as therapeutic targets.

Translational Insights Into Peroxisome Proliferator-Activated Receptors in Experimental Acute Pancreatitis

Acute pancreatitis (AP) is an inflammatory disorder of the exocrine pancreas frequently associated with metabolic causes, contributing factors, or consequences, including hypertriglyceridemia, obesity, and disorders of intermediary metabolism, respectively. To date, there is no specific therapy for this disease. Future optimal therapy should correct both inflammatory and metabolic components of the disease. Peroxisome proliferator-activated receptors (PPARs) are lipid-sensing nuclear receptors that control inflammatory and metabolic pathways via ligand-dependent and ligand-independent mechanisms. There are 3 known subtypes, PPAR-α, PPAR-β/δ, and PPAR-γ, which are differentially expressed in various tissues. The PPARs interact closely with other transcription factors such as nuclear factor κB and signal tranducers and activators of transcription that have pivotal roles in the pathobiology of AP. In this comprehensive review, we summarize the role of PPARs in AP, highlighting important in vitro and in vivo experimental findings. Finally, we propose future research directions as well as potential translational use of PPAR agonists in the treatment of AP.

Lipids generated during acute pancreatitis increase inflammatory status of macrophages by interfering with their M2 polarization

BACKGROUND

Necrosis of adipose tissue is a common complication of acute pancreatitis. The areas of steatonecrosis become a source of inflammatory mediators, including chemically modified fatty acids which could influence the progression of the systemic inflammation. In an experimental model of acute pancreatitis we analyzed the effects of lipids generated by two representative areas of adipose tissue on the switch to the M1 phenotype in macrophages.

METHODS

Pancreatitis was induced in rats by intraductal administration of 5% taurocholate and after 6 h, lipids from retroperitoneal, mesenteric or epididymal adipose tissues were collected. Lipid uptake, phenotype polarization and the activation of PPARγ and NFκB were evaluated in macrophages treated with these lipids.

RESULTS

After induction of pancreatitis, lipids from visceral adipose tissue promote the switch to an increased pro-inflammatory phenotype in macrophages. This effect is not related with a higher activation of NFκB but with an interfering effect on the activation of M2 phenotype.

CONCLUSIONS

During acute pancreatitis, lipids generated by some areas of adipose tissue interfere on the M2 polarization of macrophages, thus resulting in a more intense pro-inflammatory M1 response.

Pancreastatin-dependent inflammatory signaling mediates obesity-induced insulin resistance

Chromogranin A knockout (Chga-KO) mice exhibit enhanced insulin sensitivity despite obesity. Here, we probed the role of the chromogranin A-derived peptide pancreastatin (PST: CHGA(273-301)) by investigating the effect of diet-induced obesity (DIO) on insulin sensitivity of these mice. We found that on a high-fat diet (HFD), Chga-KO mice (KO-DIO) remain more insulin sensitive than wild-type DIO (WT-DIO) mice. Concomitant with this phenotype is enhanced Akt and AMPK signaling in muscle and white adipose tissue (WAT) as well as increased FoxO1 phosphorylation and expression of mature Srebp-1c in liver and downregulation of the hepatic gluconeogenic genes, Pepck and G6pase. KO-DIO mice also exhibited downregulation of cytokines and proinflammatory genes and upregulation of anti-inflammatory genes in WAT, and peritoneal macrophages from KO mice displayed similarly reduced proinflammatory gene expression. The insulin-sensitive, anti-inflammatory phenotype of KO-DIO mice is masked by supplementing PST. Conversely, a PST variant peptide PSTv1 (PST-NΔ3: CHGA(276-301)), lacking PST activity, simulated the KO phenotype by sensitizing WT-DIO mice to insulin. In summary, the reduced inflammation due to PST deficiency prevented the development of insulin resistance in KO-DIO mice. Thus, obesity manifests insulin resistance only in the presence of PST, and in its absence obesity is dissociated from insulin resistance.

A systematic review of acute pancreatitis as an adverse event of type 2 diabetes drugs: from hard facts to a balanced position

The question whether antidiabetes drugs can cause acute pancreatitis dates back to the 1970s. Recently, old concerns have re-emerged following claims that use of incretins, a new class of drugs for type 2 diabetes, might increase the relative risk of acute pancreatitis up to 30-fold. Given that diabetes is per se a potent risk factor for acute pancreatitis and that drug-related acute pancreatitis is rare and difficult to diagnose, we searched the medical databases for information linking acute pancreatitis and type 2 diabetes drugs. Among the biguanides, both phenformin and metformin (the latter in patients with renal insufficiency) have been cited in case reports as a potential cause of acute pancreatitis. Sulphonylureas, as both entire class and single compound (glibenclamide), have also been found in cohort studies to increase its risk. No direct link was found between pancreatic damage and therapy with metaglinide, acarbose, pramlintide or SGLT-2 inhibitors. In animal models, thiazolinediones have demonstrated proprieties to attenuate pancreatic damage, opening perspectives for their use in treating acute pancreatitis in humans. Several case reports and the US Food and Drug Administration pharmacovigilance database indicate an association between acute pancreatitis and incretins, dipeptidyl peptidase-4 (DPP-4) inhibitors, and GLP-1 receptor agonists. To date, however, a clear-cut odds ratio for this association has been reported in only one of eight pharmacoepidemiological studies. Finally, none of the intervention trials investigating these compounds, including two large randomized controlled trials with cardiovascular endpoints, confirmed the purportedly increased risk of acute pancreatitis with incretin use.

Inhibition of the nucleotide-binding domain, leucine-rich containing family, pyrin-domain containing 3 inflammasome reduces the severity of experimentally induced acute pancreatitis in obese mice

Acute pancreatitis (AP), although most often a mild and self-limiting inflammatory disease, worsens to a characteristically necrotic severe acute pancreatitis (SAP) in about 20% of cases. Obesity, affecting more than one-third of American adults, is a risk factor for the development of SAP, but the exact mechanism of this association has not been identified. Coincidental with chronic low-grade inflammation, activation of the nucleotide-binding domain, leucine-rich containing family, pyrin-domain containing 3 (NLRP3) inflammasome increases with obesity. Lean mice genetically deficient in specific components of the NLRP3 inflammasome are protected from experimentally induced AP, indicating a direct involvement of this pathway in AP pathophysiology. We hypothesized that inhibition of the NLRP3 inflammasome with the sulfonylurea drug glyburide would reduce disease severity in obese mice with cerulein-induced SAP. Treatment with glyburide led to significantly reduced relative pancreatic mass and water content and less pancreatic damage and cell death in genetically obese ob/ob mice with SAP compared with vehicle-treated obese SAP mice. Glyburide administration in ob/ob mice with cerulein-induced SAP also resulted in significantly reduced serum levels of interleukin 6, lipase, and amylase and led to lower production of lipopolysaccharide-stimulated interleukin 1β release in cultured peritoneal cells, compared with vehicle-treated ob/ob mice with SAP. Together, these data indicate involvement of the NLRP3 inflammasome in obesity-associated SAP and expose the possible utility of its inhibition in prevention or treatment of SAP in obese individuals.

Therapeutic administration of orlistat, rosiglitazone, or the chemokine receptor antagonist RS102895 fails to improve the severity of acute pancreatitis in obese mice

OBJECTIVE

Currently, there is no therapy for severe acute pancreatitis (AP) except for supportive care. The lipase inhibitor orlistat, the peroxisome proliferator-activated receptor γ agonist rosiglitazone, and the chemokine receptor 2 antagonists attenuate the severity of AP in rodents if administered before or at the time of induction of pancreatitis. However, it is unknown whether these treatments are effective if administered therapeutically after induction of pancreatitis.

METHODS

Male C57BL6 mice with diet-induced obesity received 2 injections of mrIL-12 (150 ng per mouse) and mrIL-18 (750 ng per mouse) intraperitoneally at 24-hour intervals. The mice were injected 2, 24, and 48 hours after the second injection of IL-12 + IL-18 with orlistat (2 mg per mouse), rosiglitazone (0.4 mg per mouse), RS102895 (0.3 mg per mouse), or vehicle (20 μL of DMSO and 80 μL of canola oil) and euthanized after 72 hours.

RESULTS

Orlistat decreased intra-abdominal fat necrosis compared with vehicle (P < 0.05). However, none of the drug treatments produced significant decreases in pancreatic edema, acinar necrosis, or intrapancreatic fat necrosis.

CONCLUSIONS

Drugs previously shown to improve the severity of AP when given before or at the time of induction of pancreatitis failed to do so when administered therapeutically in the IL-12 + IL-18 model.

Potential influence of intravenous lipids on the outcomes of acute pancreatitis

Parenteral nutrition (PN) has been associated with a higher rate of adverse outcomes compared with enteral feeding in patients with acute pancreatitis (AP). However, PN may be necessary when feeding via the enteral route is poorly tolerated or impossible, and PN is recommended as a second-line nutrition therapy in AP. Intravenous (IV) lipids are commonly used as a part of PN in patients with AP. While the adverse outcomes related to the use of PN in AP have commonly been attributed to infectious complications, data suggest that the unsaturated fatty acids in the triglycerides used in IV lipids may contribute to the development of organ failure. We discuss the clinical and experimental data on this issue and the alternative lipid emulsions that are being studied.

Semantic MEDLINE for discovery browsing: using semantic predications and the literature-based discovery paradigm to elucidate a mechanism for the obesity paradox

Applying the principles of literature-based discovery (LBD), we elucidate the paradox that obesity is beneficial in critical care despite contributing to disease generally. Our approach enhances a previous extension to LBD, called "discovery browsing," and is implemented using Semantic MEDLINE, which summarizes the results of a PubMed search into an interactive graph of semantic predications. The methodology allows a user to construct argumentation underpinning an answer to a biomedical question by engaging the user in an iterative process between system output and user knowledge. Components of the Semantic MEDLINE output graph identified as "interesting" by the user both contribute to subsequent searches and are constructed into a logical chain of relationships constituting an explanatory network in answer to the initial question. Based on this methodology we suggest that phthalates leached from plastic in critical care interventions activate PPAR gamma, which is anti-inflammatory and abundant in obese patients.

Glitazones exert multiple effects on β-cell stimulus-secretion coupling

Earlier studies suggest that glitazones exert beneficial effects in patients with type 2 diabetes by directly affecting insulin secretion of β-cells, besides improving the effectiveness of insulin in peripheral tissues. The effects of glitazones on stimulus-secretion coupling (SSC) are poorly understood. We tested the influence of troglitazone and pioglitazone on different parameters of SSC, including insulin secretion (radioimmunoassay), cell membrane potential, various ion currents (patch-clamp), mitochondrial membrane potential (ΔΨ), and cytosolic Ca(2+) concentration (fluorescence). Troglitazone exerted stimulatory, inhibitory, or no effects on insulin secretion depending on the drug and glucose concentration. It depolarized the ΔΨ, thus lowering ATP production, which resulted in opening of ATP-dependent K(+) channels (K(ATP) channels) and reduced insulin secretion. However, it also exerted direct inhibitory effects on K(ATP) channels that can explain enhanced insulin secretion. Troglitazone also inhibited the currents through voltage-dependent Ca(2+) and K(+) channels. Pioglitazone was less effective than troglitazone on all parameters tested. The effects of both glitazones were markedly reduced in the presence of bovine serum albumin. Glitazones exert multiple actions on β-cell SSC that have to be considered as undesired side effects because the influence of these compounds on β-cells is not controllable. The final effect on insulin secretion depends on many parameters, including the actual glucose and drug concentration, protein binding of the drug, and the drug by itself. Troglitazone and pioglitazone differ in their influence on SSC. It can be assumed that the effects of pioglitazone on β-cells are negligible under in vivo conditions.