A murine model of obesity implicates the adipokine milieu in the pathogenesis of severe acute pancreatitis

Pathophysiological Mechanisms and Clinical Associations of Non-Alcoholic Fatty Pancreas Disease

Non-Alcoholic Fatty Pancreas disease (NAFPD), characterized by fat accumulation in pancreatic tissue, is an emerging clinical entity. However, the clinical associations, the underlying molecular drivers, and the pathophysiological mechanisms of NAFPD have not yet been characterized in detail. The NAFPD spectrum not only includes infiltration and accumulation of fat within and between pancreatic cells but also involves several inflammatory processes, dysregulation of physiological metabolic pathways, and hormonal defects. A deeper understanding of the underlying molecular mechanisms is key to correlate NAFPD with clinical entities including non-alcoholic fatty liver disease, metabolic syndrome, diabetes mellitus, atherosclerosis, as well as pancreatic cancer and pancreatitis. The aim of this review is to examine the pathophysiological mechanisms of NAFPD and to assess the possible causative/predictive risk factors of NAFPD-related clinical syndromes.

Role of obesity in pathogenesis of acute pancreatitis

Acute pancreatitis (AP) is one of the most common digestive disorders that cause hospitalization. While most of patients with AP have a mild to moderate disease and recover rapidly, about 20% of patients with AP have a severe disease and experience substantial morbidity and mortality from local and/or systemic compli-cations. The incidence of obesity has increased worldwide, and its epidemiological characteristics and rising trend are consistent with those of AP. Therefore, obesity has probably contributed to the increase in the incidence and severity of AP. However, previous studies have generated conflicting results, and some studies demonstrated that obesity is a protective factor in patients with AP. Here we discuss the role of obesity in the pathogenesis of AP and the underlying mechanisms based on clinically relevant studies.

Fatty pancreas was associated with a higher acute pancreatitis Systemic Inflammatory Response Syndrome score at hospital admission

BACKGROUND

Pancreatic fat infiltration was shown to be linked with acute pancreatitis and probably its severity. These interesting findings merit more investigation to elucidate the effect of fatty pancreas on acute pancreatitis severity.

METHODS

We performed a retrospective study of patients hospitalized with documented acute pancreatitis. Pancreatic fat was determined according to pancreas attenuation on computed tomography. Patients were divided into two groups, with and without fatty pancreas. The Systemic Inflammatory Response Syndrome (SIRS) score was compared.

RESULTS

Overall, 409 patients were hospitalized with acute pancreatitis. Among them, 48 patients had fatty pancreas (group A), vs. 361 patients who did not (group B). The mean ± SD age in group A was 54.6 ± 21.3, vs. 57.6 ± 16.8 in group B ( P  = 0.51). Patients in group A, had a significantly higher rate of fatty liver, as compared to group B (85.4% vs. 35.5%, P  < 0.001). There was no significant difference in the medical history among the two groups. Fatty pancreas was associated with more severe acute pancreatitis as assessed by SIRS score at admission. The mean ± SD of SIRS score was significantly higher in group A (0.92 ± 0.87), as compared to 0.59 ± 0.74 in group B ( P  = 0.009). Positive SIRS score was present in a significantly higher proportion of patients with fatty pancreas (25%), as compared to only 11.4% in group B ( P  = 0.02).

CONCLUSION

The occurrence of acute pancreatitis with higher SIRS score was significantly associated with fatty pancreas. Fatty pancreas may represent a predictor of acute pancreatitis severity.

Circulating monocytes in acute pancreatitis

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

Simple risk score to predict the likelihood of a positive EUS in idiopathic acute pancreatitis

BACKGROUND AND AIMS

We sought to derive a risk score, DORM65, of known variables to predict the likelihood of a positive EUS in patients with idiopathic acute pancreatitis (IAP).

METHODS

A retrospective cohort study of 180 patients with IAP was performed across 3 tertiary care centers between January 2018 and December 2021. Multivariate logistic regression modeling was performed to predict a positive EUS. Accuracy of the models was assessed by the area under the receiver-operating characteristic curve (AUROCC).

RESULTS

The diagnostic yield of EUS was 58.9% (95% confidence interval [CI], 51.7-66.1). The DORM65 scores of 5 predictors present before EUS with the best discrimination were a delayed EUS (defined as ≥82 days from the last episode of AP), obesity, not having had a repeated transabdominal US, male sex, and age ≥65 years at the time of EUS. For those at the lowest risk score group, the positive EUS rate was 13.0% compared with 100% in those at the highest risk group (relative risk, 7.67; P < .001). A score of 3 or more had a positive predictive value of 86.0% with a sensitivity of 34.9% and specificity of 91.9%. The model had a high predictive accuracy (AUROCC, .774; 95% CI, .707-.841). Adding 3 additional predictors (no cholecystectomy, no MRCP, and a single episode of AP) did not increase the accuracy significantly (AUROCC, .805; 95% CI, .742-.867).

CONCLUSIONS

DORM65 is easily calculated and accurately predicts a positive EUS in patients with IAP. Further validation is needed.

Obesity Worsens Local and Systemic Complications of Necrotizing Pancreatitis and Prolongs Disease Course

BACKGROUND

Obesity is epidemic in the USA. Limited data exist examining obesity's influence on necrotizing pancreatitis (NP) disease course.

METHODS

Retrospective review of prospectively maintained database of 571 adult necrotizing pancreatitis patients treated between 2007 and 2018. Patients were grouped according to body mass index (BMI) at disease onset. Patient characteristics, necrotizing pancreatitis course, and outcomes were compared between non-obese (BMI < 30) and obese (BMI > 30) patients.

RESULTS

Among 536 patients with BMI data available, 304 (57%) were obese (BMI > 30), and 232 (43%) were non-obese (BMI < 30). NP etiology in the obese group was more commonly biliary (55% versus 46%, p = 0.04) or secondary to hypertriglyceridemia (10% versus 2%, p < 0.001) and less commonly alcohol (17% versus 26%, p = 0.01). Obese patients had a higher incidence of baseline comorbid disease. The CT severity index was similar between groups though obese patients had a higher rate of > 50% pancreatic gland necrosis (27% versus 19%, p = 0.02). The rates of infected necrosis and organ failure were higher among obese patients. Percutaneous drainage was more common in obese patients. Time to first necrosis intervention was earlier with increasing BMI. NP disease duration was longer in obese patients. The overall mortality rate of non-obese and obese patients did not differ. However, mortality rate increased with increasing BMI.

CONCLUSION

Necrotizing pancreatitis in obese patients is characterized by a prolonged disease course, a higher risk of organ failure, infected necrosis, and the need for early necrosis-related intervention. Mortality increases with increasing BMI.

Ectopic fat deposition and its related abnormalities of lipid metabolism followed by nonalcoholic fatty pancreas

Background and Objectives

The positive energy balance between caloric intake and caloric output increasing storage of triglycerides (TG) in adipocytes has made nonalcoholic fatty liver disease (NAFLD) one of the major public health problems in China. Excessive lipid deposition in the pancreas is referred to as nonalcoholic fatty pancreas disease (NAFPD). Early assessment of pancreatic fat infiltration will have an increasing role in the clinical management of the metabolic dysregulation and prevention pancreatic complications.

Subjects and Methods

We retrospectively collected data of inpatients with NAFPD from EUS database between September 2012 and August 2020 at our endoscopic center. The prevalence of NAFPD and factors associated with its development were statistically analyzed. The echogenicity of the pancreas was compared to that of the left renal cortex during the EUS examination by using an existing criterion.

Results

Four thousand, seven hundred and four consecutive individuals underwent EUS were enrolled. The prevalence of NAFPD was 1.2% (57/4704) . Factors independently associated with NAFPD on multivariate analysis were increasing TG (odds ratios [OR] 4.65, P = 0.014), NAFLD (OR 16.76, P = 0.005) and decreasing apolipoprotein A-1 (OR 0.002, P = 0.0127). We found no association between NAFPD and age, sex, total cholesterol or hypertension.

Conclusions

We found a meaningful relationship between NAFLD, dyslipidemia, and NAFPD in Chinese. We hypothesized that NAFPD was strongly correlated with ectopic fat deposition and its related abnormalities of lipid metabolism. Early diagnosis of NAFLD provides opportunities to control the progression of NAFPD.

Current epidemiological trends and in-hospital mortality of acute pancreatitis in Germany: a systematic analysis of standardized hospital discharge data between 2008 and 2017

BACKGROUND

Acute pancreatitis (AP) represents a common gastrointestinal disorder. Complicated disease courses in particular still represent a major clinical challenge and are associated with high mortality. Evaluation of existing data sets and their careful interpretation can support a rational discussion to optimize outcomes of this common gastrointestinal disease.

METHODS

We used standardized hospital discharge data provided by the Federal Statistical Office of Germany to evaluate hospital mortality and current developments of AP in Germany between 2008 and 2017.

RESULTS

In this analysis, 516,618 hospitalized AP cases were included. Main disease etiologies featured biliary (29.9%) and alcoholic (22.7%) AP. The annual frequency of AP increased from 48,858 (2008) to 52,611 (2017), mainly due to a rising incidence of biliary AP. Average hospital mortality was 2.85% and significantly improved over time. While uncomplicated AP had low hospital mortality (1.38%), the presence of organ complications was associated with a mortality of 12.34%. The necessity of mechanical ventilation dramatically increased hospital mortality to 44.06%. Hospital mortality was significantly higher in female patients (3.31%) than males (2.55%) and showed a stepwise increase with patient age. We further identified type 2 diabetes mellitus and obesity as factors associated with increased hospital mortality. Hospital mortality was lowest among patients treated at departments specializing in gastroenterology. Finally, high case volume centers (defined as >98 annual AP cases) had the lowest hospital mortality for patients with complicated courses of AP.

CONCLUSION

With over 50,000 annual hospitalization cases, AP is one of the most important inpatient treatment indications in gastroenterology in Germany. Overall, AP mortality has improved in recent years, presumably due to improved interdisciplinary treatment concepts. In this study, we identified important clinical and epidemiological risk factors for an unfavorable course, which could help to improve risk prediction and triaging, and thus the management of AP.

Nonalcoholic fatty pancreas disease: An emerging clinical challenge

Nonalcoholic fatty pancreas disease (NAFPD) is an emerging disease that has gained an increasing amount of attention in recent years. It describes fat accumulation in the pancreas with insignificant alcohol consumption, but the pathogenesis is largely unknown. A wide range of terms have been used to describe the phenomenon of pancreatic fat accumulation, but NAFPD remains an under-recognized and non-independent disorder. Obesity, age, sex, race, and unhealthy lifestyle are established independent risk factors for NAFPD, which is strongly associated with metabolic syndrome, type 2 diabetes, pancreatitis, pancreatic fistula, pancreatic cancer, and nonalcoholic fatty liver disease. At present, imaging techniques are common diagnostic aids, but uniform criteria and consensus are lacking. Therapeutically, healthy diet, weight loss, and exercise are the mainstays to reduce pancreatic fat accumulation. It can be seen that there is a limited understanding of NAFPD at this stage and further exploration is needed. Previous studies have revealed that NAFPD may directly affect diagnosis and clinical decision-making. Therefore, exploring the pathophysiological mechanism and clinical associations of NAFPD is a major challenge for researchers and clinicians.

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.

Therapeutic Use of Adipose-Derived Stromal Cells in a Murine Model of Acute Pancreatitis

BACKGROUND

No specific therapy exists for acute pancreatitis (AP), and current treatment remains entirely supportive. Adipose stem cells (ASCs) have significant immunomodulatory and regenerative activities. We hypothesized that systemic administration of ASCs would mitigate inflammation in AP.

METHODS

AP was induced in mice by 6 hourly intraperitoneal injections of cerulein. Twenty-four hours after AP induction, mice were randomized into four systemic treatment groups: sham group (no acute pancreatitis), vehicle, human ASCs, and human ASC-conditioned media. Mice were sacrificed at 48 h, and blood and organs were collected and analyzed. Pancreatic injury was quantified histologically using a published score (edema, inflammation, and necrosis). Pancreatic inflammation was also studied by immunohistochemistry and PCR.

RESULTS

When using IV infusion of Hoechst-labeled ASCs, ASCs were found to localize to inflamed tissues: lungs and pancreas. Mice treated with ASCs had less severe AP, as shown by a significantly decreased histopathology score (edema, inflammation, and necrosis) (p = 0.001). ASCs infusion polarized pancreatic macrophages toward an anti-inflammatory M2 phenotype. ASC-conditioned media reduced pancreatic inflammation similarly to ASCs only, highlighting the importance of ASCs secreted factors in modulating inflammation.

CONCLUSION

Intravenous delivery of human ASCs markedly reduces pancreatic inflammation in a murine model of AP ASCs which represent an effective therapy for AP.

Leptin and Immunological Profile in Obesity and Its Associated Diseases in Dogs

Growing scientific evidence has unveiled increased incidences of obesity in domestic animals and its influence on a plethora of associated disorders. Leptin, an adipokine regulating body fat mass, represents a key molecule in obesity, able to modulate immune responses and foster chronic inflammatory response in peripheral tissues. High levels of cytokines and inflammatory markers suggest an association between inflammatory state and obesity in dogs, highlighting the parallelism with humans. Canine obesity is a relevant disease always accompanied with several health conditions such as inflammation, immune-dysregulation, insulin resistance, pancreatitis, orthopaedic disorders, cardiovascular disease, and neoplasia. However, leptin involvement in many disease processes in veterinary medicine is poorly understood. Moreover, hyperleptinemia as well as leptin resistance occur with cardiac dysfunction as a consequence of altered cardiac mitochondrial metabolism in obese dogs. Similarly, leptin dysregulation seems to be involved in the pancreatitis pathophysiology. This review aims to examine literature concerning leptin and immunological status in obese dogs, in particular for the aspects related to obesity-associated diseases.

Oleic acid ameliorates palmitic acid-induced ER stress and inflammation markers in naive and cerulein-treated exocrine pancreas cells

Dietary fat overload (typical to obesity) increases the risk of pancreatic pathologies through mechanisms yet to be defined. We previously showed that saturated dietary fat induces pancreatic acinar lipotoxicity and cellular stress. The endoplasmic reticulum (ER) of exocrine pancreas cells is highly developed and thus predisposed to stress. We studied the combination of saturated and unsaturated FAs in metabolic and pancreatitis like cerulein (CER)-induced stress states on cellular ER stress.

Exocrine pancreas AR42J and rat primary exocrine acinar cells underwent acute (24 h) challenge with different FAs (saturated, monounsaturated) at different concentrations (250 and 500 µM) and in combination with acute CER-induced stress, and were analyzed for fat accumulation, ER stress unfolded protein response (UPR) and immune and enzyme markers. Acute exposure of AR42J and pancreatic acinar cells to different FAs and their combinations increased triglyceride accumulation. Palmitic acid significantly dose-dependently enhanced the UPR, immune factors and pancreatic lipase (PL) levels, as demonstrated by XBP1 splicing and elevation in UPR transcripts and protein levels (Xbp1,Atf6, Atf4, Chop, Tnfα, Tgfβ and Il-6). Exposure to high palmitic levels in a CER-induced stress state synergistically increased ER stress and inflammation marker levels. Exposure to oleic acid did not induce ER stress and PL levels and significantly decreased immune factors in an acute CER-induced stress state. Combination of oleic and palmitic acids significantly reduced the palmitic-induced ER stress, but did not affect the immune factor response. We show that combination of monounsaturated and saturated FAs protects from exocrine pancreatic cellular ER stress in both metabolic and CER-induced stress.

Effect of Sheng-jiang powder on multiple-organ inflammatory injury in acute pancreatitis in rats fed a high-fat diet

BACKGROUND

Obesity worsens inflammatory organ injury in acute pancreatitis (AP), but there is no effective preventive strategy. Sheng-jiang powder (SJP) has been shown to alleviate multiple-organ inflammatory injury in rats with high-fat diet-induced obesity. Hence, SJP is supposed to have an effect on multiple-organ inflammatory injury in AP in rats fed a high-fat diet.

AIM

To explore how obesity may contribute to aggravating inflammatory organ injury in AP in rats and observe the effect of SJP on multiple-organ inflammatory injury in AP in rats fed a high-fat diet.

METHODS

Rats were randomly assigned to a control group (CG), an obese group (OG), and an SJP treatment group (SG), with eight rats per group. The rats in the OG and SG were fed a high-fat diet. From the third week, the rats in the SG were given oral doses of SJP (5 g/kg of body weight). After 12 wk, AP was induced in the three groups. Serum amylase level, body weight, Lee’s index, serum biochemistry parameters, and serum inflammatory cytokine and tissue cytokine levels were assessed, and the tissue histopathological scores were evaluated and compared.

RESULTS

Compared with the CG, serum triglyceride, total cholesterol, interleukin-6, and interleukin-10 levels were significantly higher in the OG, and serum high-density lipoprotein cholesterol level was significantly lower in the OG. Moreover, enhanced oxidative damage was observed in the pancreas, heart, spleen, lung, intestine, liver, and kidney. Evidence of an imbalanced antioxidant defense system, especially in the pancreas, spleen, and intestine, was observed in the obese AP rats. Compared with the OG, serum high-density lipoprotein cholesterol, interleukin-10, and superoxide dismutase expression levels in the pancreas, spleen, and intestine were increased in the SG. Additionally, SJP intervention led to a decrease in the following parameters: body weight; Lee’s index; serum triglyceride levels; serum total cholesterol levels; malondialdehyde expression levels in the pancreas, heart, spleen, lung, and liver; myeloperoxidase expression levels in the lung; and pathological scores in the liver.

CONCLUSION

Obesity may aggravate the inflammatory reaction and pathological multiple-organ injury in AP rats, and SJP may alleviate multiple-organ inflammatory injury in AP in rats fed a high-fat diet.

The Clinical Implications of Fatty Pancreas: A Concise Review

Fatty pancreas is a newly recognized condition which is poorly investigated until today as compared to nonalcoholic fatty liver disease. It is characterized by pancreatic fat accumulation and subsequent development of pancreatic and metabolic complications. Association of fatty pancreas have been described with type 2 diabetes mellitus, acute and chronic pancreatitis and even pancreatic carcinoma. In this review article, we provide an update on clinical implications, pathogenesis, diagnosis, treatment and outcomes.

Significance of steatosis in pancreatic transplantation

The on-going success of whole organ pancreatic transplantation is dependent on overcoming the imbalance between demand and supply of optimal organs as well as tackling the vast comorbidity associated with the procedure. Pancreas steatosis is a common contributing factor to the problem and with obesity pandemics affecting the global population; the size and type of organs received from donors will only make steatosis more of an issue. The aim of this review is to highlight what is known about steatosis in the context of pancreas transplantation identifying potential methods to help its evaluation. Narrative review of literature from inception to June 2017, using OVID interface searching EMBASE and MEDLINE databases as well recent transplant conference data. All studies related to pancreas steatosis examined for clinical relevance with no exclusion criteria. Key ideas extracted and referenced. Pancreatic steatosis is not innocuous and is precariously regarded by transplant surgeons, however its associations with obesity, metabolic syndrome and long list of associated complications clearly show it needs more careful consideration. Radiologic and surgical advances now allow assessment of the fat content of organs, which could be used to quantify organs allowing better optimisation, but there is still much work to be done to refine the optimal method to achieve this.

Associations between circulating levels of adipocytokines and abdominal adiposity in patients after acute pancreatitis

Adipocytokines are strongly associated with abdominal adiposity during the course of acute pancreatitis (AP). This study investigated associations between a panel of adipocytokines and abdominal adiposity in AP patients after hospital discharge, as well as the effect of several covariates. Fasting venous blood samples were collected to measure adiponectin, interleukin 6, leptin, monocyte chemoattractant protein 1, tumour necrosis factor α (TNFα), resistin, and retinol-binding protein 4. Waist circumference (WC), waist-hip ratio, and waist-height ratio (WheightR) were used as measures of abdominal adiposity. Generalised linear models were built, adjusting for age, sex, ethnicity, diabetes status, aetiology, duration since admission for AP, recurrence, and severity of AP. A total of 93 patients were studied, on average at 22 months after AP. Interleukin 6, TNFα, and leptin were significantly associated with WC in both the unadjusted and all the three adjusted models. Also, they were significantly associated with WheightR in both the unadjusted and the three adjusted models. Other studied adipocytokines did not show a consistent association or were not significantly associated with the abdominal adiposity indices. The results suggest that excess abdominal adiposity favours pro-inflammatory milieu in AP patients after hospital discharge, independent of diabetes and effect of other covariates.

Exploring the metabolic syndrome: Nonalcoholic fatty pancreas disease

After the first description of fatty pancreas in 1933, the effects of pancreatic steatosis have been poorly investigated, compared with that of the liver. However, the interest of research is increasing. Fat accumulation, associated with obesity and the metabolic syndrome (MetS), has been defined as “fatty infiltration” or “nonalcoholic fatty pancreas disease” (NAFPD). The term “fatty replacement” describes a distinct phenomenon characterized by death of acinar cells and replacement by adipose tissue. Risk factors for developing NAFPD include obesity, increasing age, male sex, hypertension, dyslipidemia, alcohol and hyperferritinemia. Increasing evidence support the role of pancreatic fat in the development of type 2 diabetes mellitus, MetS, atherosclerosis, severe acute pancreatitis and even pancreatic cancer. Evidence exists that fatty pancreas could be used as the initial indicator of “ectopic fat deposition”, which is a key element of nonalcoholic fatty liver disease and/or MetS. Moreover, in patients with fatty pancreas, pancreaticoduodenectomy is associated with an increased risk of intraoperative blood loss and post-operative pancreatic fistula.

Obesity-Induced Inflammation and Desmoplasia Promote Pancreatic Cancer Progression and Resistance to Chemotherapy

It remains unclear how obesity worsens treatment outcomes in patients with pancreatic ductal adenocarcinoma (PDAC). In normal pancreas, obesity promotes inflammation and fibrosis. We found in mouse models of PDAC that obesity also promotes desmoplasia associated with accelerated tumor growth and impaired delivery/efficacy of chemotherapeutics through reduced perfusion. Genetic and pharmacologic inhibition of angiotensin-II type-1 receptor reverses obesity-augmented desmoplasia and tumor growth and improves response to chemotherapy. Augmented activation of pancreatic stellate cells (PSC) in obesity is induced by tumor-associated neutrophils (TAN) recruited by adipocyte-secreted IL1β. PSCs further secrete IL1β, and inactivation of PSCs reduces IL1β expression and TAN recruitment. Furthermore, depletion of TANs, IL1β inhibition, or inactivation of PSCs prevents obesity-accelerated tumor growth. In patients with pancreatic cancer, we confirmed that obesity is associated with increased desmoplasia and reduced response to chemotherapy. We conclude that cross-talk between adipocytes, TANs, and PSCs exacerbates desmoplasia and promotes tumor progression in obesity.

SIGNIFICANCE

Considering the current obesity pandemic, unraveling the mechanisms underlying obesity-induced cancer progression is an urgent need. We found that the aggravation of desmoplasia is a key mechanism of obesity-promoted PDAC progression. Importantly, we discovered that clinically available antifibrotic/inflammatory agents can improve the treatment response of PDAC in obese hosts. Cancer Discov; 6(8); 852-69. ©2016 AACR.See related commentary by Bronte and Tortora, p. 821This article is highlighted in the In This Issue feature, p. 803.

Hormonal protection in acute pancreatitis by ghrelin, leptin and melatonin

Acute pancreatitis is a nonbacterial disease of the pancreas. The severe form of this ailment is characterized by high mortality. Whether acute pancreatitis develops as the severe type or resolves depends on the intensity of the inflammatory process which is counteracted by the recruitment of innate defense mechanisms. It has been shown that the hormones ghrelin, leptin and melatonin are able to modulate the immune function of the organism and to protect the pancreas against inflammatory damage. Experimental studies have demonstrated that the application of these substances prior to the induction of acute pancreatitis significantly attenuated the intensity of the inflammation and reduced pancreatic tissue damage. The pancreatic protective mechanisms of the above hormones have been related to the mobilization of non-specific immune defense, to the inhibition of nuclear factor kappa B and modulation of cytokine production, to the stimulation of heat shock proteins and changes of apoptotic processes in the acinar cells, as well as to the activation of antioxidant system of the pancreatic tissue. The protective effect of ghrelin seems to be indirect and perhaps dependent on the release of growth hormone and insulin-like growth factor 1. Leptin and ghrelin, but not melatonin, employ sensory nerves in their beneficial action on acute pancreatitis. It is very likely that ghrelin, leptin and melatonin could be implicated in the natural protection of the pancreatic gland against inflammatory damage because the blood levels of these substances increase in the initial phase of pancreatic inflammation. The above hormones could be a part of the innate resistance system which might remove noxious factors and could suppress or attenuate the inflammatory process in the pancreas.

Serum adipokine concentrations in dogs with acute pancreatitis

Background

Limited information is available about the role of adipokines in the development and progression of acute pancreatitis (AP) in dogs.

Objectives

To determine whether the circulating concentrations of adipokines differed between healthy dogs and dogs with AP, and whether the circulating concentrations differed between AP survivors and AP nonsurvivors.

Animals

Twenty‐eight healthy dogs and 25 client‐owned dogs with AP.

Methods

Prospective observational cohort study of 25 client‐owned dogs with newly diagnosed AP and 28 otherwise healthy dogs with similar body condition scores. The serum concentrations of leptin, adiponectin, resistin, visfatin, interleukin (IL)‐1β, IL‐6, IL‐10, IL‐18, and tumor necrosis factor (TNF)‐α were measured.

Results

The serum concentrations of leptin (P = .0021), resistin (P = .0010), visfatin (P < .0001), IL‐1β (P < .0001), IL‐6 (P = .0002), IL‐10 (P < .0001), and IL‐18 (P < .0001) were significantly higher in dogs with AP than healthy dogs, whereas the adiponectin concentration (P = .0011) was significantly lower. There were significant differences in the serum concentrations of leptin (P = .028) and adiponectin (P = .046) in survivors and nonsurvivors. After the disappearance of clinical signs, the concentrations of resistin (P = .037) and IL‐1β (P = .027) decreased significantly, whereas the serum concentrations of leptin (P > .999), adiponectin (P = .11), visfatin (P = .83), IL‐6 (P = .82), IL‐10 (P = .82), IL‐18 (P = .56), and TNF‐α (P = .94) did not differ significantly.

Conclusion and Clinical Importance

This study showed that dysregulation of adipokines might be involved in the pathogenesis of AP. In addition, leptin and adiponectin are likely to be associated with mortality rate in AP.

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.

Increased fat in pancreas not associated with risk of pancreatitis post-endoscopic retrograde cholangiopancreatography

Background

A preliminary study has shown increased pancreatic fat in patients with idiopathic pancreatitis and sphincter of Oddi dysfunction. In this study, we aimed to determine if an increased quantity of pancreatic fat is an independent risk factor for pancreatitis post-endoscopic retrograde cholangiopancreatography (ERCP).

Methods

In this case control study, we retrospectively reviewed a local radiological and ERCP database to identify patients who had had abdominal magnetic resonance imaging (MRI) followed by ERCP no more than 60 days later between September 2003 and January 2011. Percentage of fat was determined by recording signal intensity in the in-phase (S_in) and out-of-phase (S_out) T1-weighted gradient sequences, and calculation of the fat fraction as (S_in − S_out)/(S_in) × 2 by an abdominal radiologist blinded to clinical history. Controls matched for age, gender, and other pancreatobiliary disease were selected from a group with no post-ERCP pancreatitis (before fat content of the pancreas was analyzed).

Results

Forty-seven patients were enrolled. Compared with controls, subjects with post-ERCP pancreatitis were similar in terms of age (41.4 years versus 41.1 years), gender (21.2% versus 20.2% males), pancreatobiliary disease characteristics, and most ERCP techniques. Measurements of pancreatic head, body, and tail fat and body mass index were similar in patients and controls.

Conclusion

Increased pancreatic fat on MRI criteria is not an independent predictor of post-ERCP pancreatitis.

Adipose tissue dendritic cells enhances inflammation by prompting the generation of Th17 cells

BACKGROUND

Obesity has become a global challenge for public health. It has been reported that obesity is associated with chronic inflammation. However, the mechanism for the chronic inflammation contributes to obesity remains elusive.

METHODOLOGY/PRINCIPAL FINDINGS

In our study, we found a novel CD11c+ dendritic cell subset existed in murine adipose tissues which was immature phenotype. Moreover, as compared to the lean controls, the number of CD11c+ DCs and CD4+IL-17+T cells were higher in adipose tissue of high fat diet (HFD) mice. Adipose tissues derived dendritic cells (ATDCs) displayed lower levels of CD40, CD80, CD86, MHCI and MHCII expression than splenic DCs (SPDCs). However, ATDCs showed higher levels of IL-6, TGF-β and IL-23 secretion. Moreover, our in vitro experiments demonstrated that ATDCs were capable of promoting Th17 cell generation.

CONCLUSIONS/SIGNIFICANCE

Our results indicate the existence of CD11c+ DCs in adipose tissues, which displays an immature phenotype but possessing pro-inflammatory function.

Risk factors for pancreatic cancer: underlying mechanisms and potential targets

PURPOSE OF THE REVIEW

Pancreatic cancer is extremely aggressive, forming highly chemo-resistant tumors, and has one of the worst prognoses. The evolution of this cancer is multi-factorial. Repeated acute pancreatic injury and inflammation are important contributing factors in the development of pancreatic cancer. This article attempts to understand the common pathways linking pancreatitis to pancreatic cancer.

RECENT FINDINGS

Intracellular activation of both pancreatic enzymes and the transcription factor NF-κB are important mechanisms that induce acute pancreatitis (AP). Recurrent pancreatic injury due to genetic susceptibility, environmental factors such as smoking, alcohol intake, and conditions such as obesity lead to increases in oxidative stress, impaired autophagy and constitutive activation of inflammatory pathways. These processes can stimulate pancreatic stellate cells, thereby increasing fibrosis and encouraging chronic disease development. Activation of oncogenic Kras mutations through inflammation, coupled with altered levels of tumor suppressor proteins (p53 and p16) can ultimately lead to development of pancreatic cancer.

SUMMARY

Although our understanding of pancreatitis and pancreatic cancer has tremendously increased over many years, much remains to be elucidated in terms of common pathways linking these conditions.

Inflammation, autophagy, and obesity: common features in the pathogenesis of pancreatitis and pancreatic cancer

Inflammation and autophagy are cellular defense mechanisms. When these processes are deregulated (deficient or overactivated) they produce pathologic effects, such as oxidative stress, metabolic impairments, and cell death. Unresolved inflammation and disrupted regulation of autophagy are common features of pancreatitis and pancreatic cancer. Furthermore, obesity, a risk factor for pancreatitis and pancreatic cancer, promotes inflammation and inhibits or deregulates autophagy, creating an environment that facilitates the induction and progression of pancreatic diseases. However, little is known about how inflammation, autophagy, and obesity interact to promote exocrine pancreatic disorders. We review the roles of inflammation and autophagy, and their deregulation by obesity, in pancreatic diseases. We discuss the connections among disordered pathways and important areas for future research.

Adipokine levels in the course of mild biliary pancreatitis

OBJECTIVES

Obesity markedly increases the risk of severe acute pancreatitis (AP). Several adipokines have been ascribed a role as a predictor of clinical severity in AP. Therefore, the aim of this study was to investigate a possible relationship between leptin and adiponectin and mild biliary AP.

METHODS

We included 24 consecutive patients with mild biliary AP and 24 consecutive healthy age- and sex-matched controls. Clinical severity was classified by the Ranson score. ELISA was used to assess leptin and adiponectin levels on admission and in remission. Complete blood cell counts and other laboratory tests were also performed at baseline and in remission.

RESULTS

Leptin, adiponectin, insulin and HOMA-IR measurements showed no difference in pancreatitis patients both on admission and in remission compared to the control group. No difference was found in leptin, insulin or HOMA-IR levels in the course of pancreatitis. However, adiponectin levels were higher in remission compared to admission.

CONCLUSIONS

Increased adiponectin levels in remission may be an indication of improvement in this condition. Further studies are needed to determine whether adiponectin provides protection from AP.

Age-dependent vulnerability to experimental acute pancreatitis is associated with increased systemic inflammation and thrombosis

The severity and mortality rates of acute pancreatitis (AP) are significantly elevated in the elderly population. However, due to a lack of appropriate animal models, the underlying mechanisms for this age-dependent vulnerability remain largely unknown. The purpose of this study was to characterize a murine model of AP, which displays age-associated severity, and to use this model to identify pathophysiologies that are distinctive of the aged with AP. AP was induced in young (4-5 months), middle-aged (12-13 months), and aged (23-25 months) C57BL/6 mice by repeated injection of caerulein, a homologue of the gastrointestinal hormone cholecystokinin. Approximately 10% of aged mice died during AP, while young and middle-aged mice showed no mortality. Although both young and aged mice exhibited early signs of edema and inflammation in the pancreas, kidney, and lung, young mice showed signs of recovery within 24 h, while aged mice exhibited increasingly severe tissue damage and cell death. There was a significant age-dependent increase in pancreatic neutrophil activation and systemic inflammation as assessed by pancreatic myeloperoxidase and plasma interleukin-6 (IL-6) concentration, respectively. Importantly, aged but not young mice with AP showed significantly elevated thrombosis in the lung and kidney as well as a marked increase in plasma concentration of plasminogen activator inhibitor-1 (PAI-1), a primary inhibitor of the fibrinolytic system. These results demonstrate that aging is associated with increased severity of AP characterized by augmented and prolonged pancreatic inflammation and the presence of multiple extra-pancreatic sequelae including thrombosis.

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

Obesity increases severity of acute pancreatitis (AP) by unclear mechanisms. We investigated the effect of the PPAR-gamma agonist rosiglitazone (RGZ, 0.01% in the diet) on severity of AP induced by administration of IL-12+ IL-18 in male C57BL6 mice fed a low fat (LFD) or high fat diet (HFD), under the hypothesis that RGZ would reduce disease severity in HFD-fed obese animals. In both LFD and HFD mice without AP, RGZ significantly increased body weight and % fat mass, with significant upregulation of adiponectin and suppression of erythropoiesis. In HFD mice with AP, RGZ significantly increased survival and hastened recovery from pancreatic inflammation, as evaluated by significantly improved pancreatic histology, reduced saponification of visceral adipose tissue and less severe suppression of erythropoiesis at Day 7 post-AP. This was associated with significantly lower circulating and pancreas-associated levels of IL-6, Galectin-3, osteopontin and TIMP-1 in HFD + RGZ mice, particularly at Day 7 post-AP. In LFD mice with AP, RGZ significantly worsened the degree of intrapancreatic acinar and fat necrosis as well as visceral fat saponification, without affecting other parameters of disease severity or inflammation. Induction of AP lead to major suppression of adiponectin levels at Day 7 in both HFD and HFD + RGZ mice. In conclusion, RGZ prevents development of severe AP in obese mice even though it significantly increases adiposity, indicating that obesity can be dissociated from AP severity by improving the metabolic and inflammatory milieu. However, RGZ worsens selective parameters of AP severity in LFD mice.

Role of IL-6 in the resolution of pancreatitis in obese mice

Obesity increases severity of acute pancreatitis and risk of pancreatic cancer. Pancreatitis and obesity are associated with elevated IL-6, a cytokine involved in inflammation and tumorigenesis. We studied the role of IL-6 in the response of lean and obese mice to pancreatitis induced by IL-12 + IL-18. Lean and diet-induced obese (DIO) WT and IL-6 KO mice and ob/ob mice pretreated with anti-IL-6 antibodies were evaluated at Days 1, 7, and 15 after induction of pancreatitis. Prolonged elevation of IL-6 in serum and visceral adipose tissue was observed in DIO versus lean WT mice, whereas circulating sIL-6R declined in DIO but not lean mice with pancreatitis. The severe inflammation and lethality of DIO mice were also observed in IL-6 KO mice. However, the delayed resolution of neutrophil infiltration; sustained production of CXCL1, CXCL2, and CCL2; prolonged activation of STAT-3; and induction of MMP-7 in the pancreas, as well as heightened induction of serum amylase A of DIO mice, were blunted significantly in DIO IL-6 KO mice. In DIO mice, production of OPN and TIMP-1 was increased for a prolonged period, and this was mediated by IL-6 in the liver but not the pancreas. Results obtained in IL-6 KO mice were confirmed in ob/ob mice pretreated with anti-IL-6 antibodies. In conclusion, IL-6 does not contribute to the increased severity of pancreatitis of obese mice but participates in delayed recovery from acute inflammation and may favor development of a protumorigenic environment through prolonged activation of STAT-3, induction of MMP-7, and sustained production of chemokines.

Acute pancreatitis in obesity: adipokines and dietary fish oil

BACKGROUND

Acute pancreatitis is a substantial clinical problem accounting for 240,000 hospital admissions yearly in the United States. Obesity is epidemic and is clearly an independent risk factor for increased severity of acute pancreatitis (AP). Adipose tissue is an endocrine organ that secretes a variety of metabolically active substances termed adipokines. However, the role of adipokines in modulating acute pancreatitis severity remains incompletely understood. Dietary fish oil is rich in omega-3 free fatty acids and attenuates adipose tissue-induced inflammation. Therefore, we hypothesized that feeding obese mice diets rich in fish oil would alter the adipokine milieu and attenuate the severity of pancreatitis.

METHODS

Lean (C57BL/6 J) and obese (LepDb) mice were fed either a soybean oil- or fish oil-rich diet for 4 weeks. AP was induced by six hourly intraperitoneal injections of cerulein (50 μg/kg). Serum adipokine levels were measured, and pancreatitis severity was assessed histologically and by measuring pancreatic concentrations of interleukin-1 beta (IL-1β), interleukin-6 (IL-6), myleoperoxidase (MPO), and monocyte chemoattractant protein-1 (MCP-1).

RESULTS

Obese mice developed more severe pancreatitis than lean mice. Fish oil significantly decreased serum leptin (lean and obese) and increased serum adiponectin (lean only). Fish oil did not alter the baseline pancreatic inflammatory milieu, nor did it change histologic or biochemical pancreatitis severity.

CONCLUSION

These data demonstrate that a diet rich in fish oil altered the adipokine milieu in lean and congenitally obese mice; however, fish oil did not improve pancreatitis severity induced with cerulein hyperstimulation.

Does adiponectin upregulation attenuate the severity of acute pancreatitis in obesity?

INTRODUCTION

Obesity is an independent risk factor for severe acute pancreatitis, though the mechanisms underlying this association are unknown. The powerful anti-inflammatory adipokine adiponectin is decreased in obesity. We recently showed that the severity of pancreatitis in obese mice is inversely related to circulating adiponectin levels, and therefore hypothesized that adiponectin upregulation would attenuate the severity of pancreatitis in obese mice.

METHODS

Forty congenitally obese mice were studied. Seven days prior to study, 20 mice received a single tail vein injection of adenovirus expressing recombinant murine adiponectin (APN; 2 × 10⁸ plaque forming unit (pfu)), and the remainder received a control adenoviral vector expressing β-galactosidase (β-gal; 2 × 10⁸ pfu). Half of the mice in each group had pancreatitis induced by cerulein injection (50 mcg/kg IP hourly for 6 h). The other half received saline on the same schedule. Serum APN concentration and pancreatic tissue concentrations of interleukin (IL)-6, IL-1β, and MCP-1 were measured by ELISA. Histologic pancreatitis score was calculated based on the degree of inflammation (0-4), edema (0-4), and vacuolization (0-4). Data were analyzed by ANOVA and Tukey's tests; p < 0.05 was considered significant.

RESULTS

No difference in body weight was observed between groups. Serum APN was significantly upregulated in the APN group compared with the β-gal group. Pancreatic tissue concentration of IL-6 was significantly decreased in the APN group compared with the β-gal group. No change either in pancreatic tissue concentration of IL-1β and MCP-1 or in the severity of histologic pancreatitis were observed.

CONCLUSION

Adiponectin upregulation modulates the pancreatic cytokine milieu but does not attenuate pancreatitis in this model of mild acute pancreatitis.

Jinhuangyidan down-regulates ICAM-1 expression but up-regulates TGF-β1 expression in severe acute pancreatitis in rats

AIM: To investigate the effect of Jinhuangyidan on the expression of intercellular cell adhesion molecule-1 (ICAM-1) and transforming growth factor-β1 (TGF-β1) in the pancreas tissue of rats with severe acute pancreatitis (SAP).

METHODS: Fifty-four male SD rats were randomly and equally divided into control group, model group and treatment group. SAP was induced in rats by retrograde injection of 5% taurocholic acid. Each group was further divided into three subgroups for testing at 2, 6 and 12 h after injection. Pathological changes in the pancreas were scored, and expression of ICAM-1 and TGF-β1 proteins in the pancreas was detected by immunohistochemistry.

RESULTS: Compared to the model group, pancreatic damage was significantly mitigated in the treatment group at 6 and 12 h (10.33 ± 0.82 vs 14.00 ± 0.63; 9.67 ± 0.82 vs 15.33 ± 0.52; both P = 0.000); the expression of ICAM-1 decreased significantly at 12 h (3.67 ± 0.76 vs 6.40 ± 0.72, P = 0.000); and the expression of TGF-β1 significantly increased at 6 and 12 h (3.77 ± 0.78 vs 0.60 ± 1.00, P = 0.00; 5.17 ± 1.42 vs 2.23 ± 1.01, both P = 0.000).

CONCLUSION: Jinhuangyidan can significantly improve early pancreatic pathological damage possibly by reducing ICAM-1 expression and increasing TGF-β1 expression in SAP in rats.

Effect of different obesogenic diets on pancreatic histology in Ossabaw miniature swine

OBJECTIVE

Obesity is a factor in the outcome and severity of pancreatic conditions. We examined the effect of hypercaloric diets on the pancreata of Ossabaw swine, a large animal model of metabolic syndrome and obesity.

METHODS

Swine were fed with 1 of 4 diets: high-fructose (n = 9), atherogenic (n = 10), modified atherogenic (n = 6), or eucaloric standard diet (n = 12) for 24 weeks. Serum chemistries were measured, and pancreata were examined for histological abnormalities including steatosis, inflammation or fibrosis, insulin content, and oxidative stress.

RESULTS

The fructose, atherogenic, and modified atherogenic diet groups exhibited obesity, metabolic syndrome, islet enlargement, and significantly increased pancreatic steatosis (22.9% ± 7.5%, 19.7% ± 7.7%, and 38.7% ± 15.3% fat in total tissue area, respectively) compared with controls (9.3% ± 1.9%; P < 0.05). The modified atherogenic diet group showed significantly increased oxidative stress levels as evidenced by elevated serum malondialdehyde (3.0 ± 3.3 vs 1.5 ± 0.3 μmol/L in controls; P = 0.006) and pancreatic malondialdehyde (0.1 ± 0.12 vs 0.04 ± 0.01 nmol/mg protein in controls; P = 0.01). None of the swine exhibited pancreatitis or cellular injury.

CONCLUSIONS

Ossabaw swine fed with a modified atherogenic diet developed significant pancreatic steatosis and increased oxidative stress, but no other histological abnormalities were observed.

The clinical significance of pancreatic steatosis

More research is now focused on pancreatic steatosis. Multiple definitions, clinical associations and synonyms for pancreatic steatosis are described in the literature and can be confusing. The integration and comparison of several studies concerning this topic is therefore challenging. In the past, pancreatic steatosis was considered an innocuous condition, a bystander of many underlying diseases (such as congenital syndromes, hemochromatosis and viral infection). However, evidence that pancreatic steatosis (strongly associated with obesity and the metabolic syndrome) has a role in type 2 diabetes mellitus, pancreatic exocrine dysfunction, acute pancreatitis, pancreatic cancer and the formation of pancreatic fistula after pancreatic surgery is emerging. This Review focuses on the different etiological factors and the clinical consequences of pancreatic steatosis.

Adipokines and cytokines in human pancreatic juice: unraveling the local pancreatic inflammatory milieu

BACKGROUND

Differential adipokine expression in obesity influences the inflammatory milieu, and may explain in part obesity's negative impact on pancreatic disease. Pancreatic juice analysis may provide a good means to evaluate the local pancreatic inflammatory milieu. The presence of adipokines in pancreatic juice is unknown.

AIMS

This proof-of-concept study was designed to determine the presence of adipokines and cytokines in human pancreatic juice.

METHODS

With institutional review board approval, pancreatic juice was obtained from ten patients with a broad range of diagnoses at the time of endoscopic retrograde cholangiopancreatography. Pancreatic juice was assayed using enzyme-linked immunosorbent assay (ELISA) for insulin, the proinflammatory adipokine leptin, the anti-inflammatory adipokine adiponectin, and the inflammatory mediators interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and monocyte chemoattractant protein-1 (MCP-1). Correlation between adipokine and inflammatory mediator expression was determined by linear regression analysis. Data are presented as mean +/- standard error of the mean (SEM); P < 0.05 was considered statistically significant.

RESULTS

Leptin (0.16 +/- 0.05 ng/ml) and adiponectin (0.63 +/- 0.02 microg/ml) were both present, as were the inflammatory mediators IL-6 (112.6 +/- 28.1 pg/ml), TNF-alpha (49.0 +/- 18.8 pg/ml), and MCP-1 (32.2 +/- 0.9 pg/ml). Paradoxically, the expression of the anti-inflammatory adipokine adiponectin correlated strongly with that of the proinflammatory cytokine IL-6 (R(2) = 0.98, P < 0.001).

CONCLUSIONS

This report is the first to describe adipokine expression in human pancreatic juice. Human pancreatic juice inflammatory mediators and adipokines may provide an important measurement of the local pancreatic inflammatory milieu.

Advances in understanding the role of inflammatory and antiinflammatory factors in the pathogenesis of acute pancreatitis

Acute pancreatitis (AP) is a common clinical disorder presenting as acute abdomen. As AP is often complicated with many other serious diseases, the overall mortality rate is high in AP patients. At present, the research on the pathogenesis of AP has attracted wide attention though it has not been fully clarified yet. Many theories, such as "self-digestion of the pancreas", "inflammatory response" and "intestinal bacterial translocation", have been proposed to explain the pathogenesis of AP. Extensive research is being conducted to investigate the relationship of inflammatory and antiinflammatory factors with AP. In this article, we will review the recent advances in understanding the role of inflammatory and antiinflammatory factors in the pathogenesis of AP.

Effect of diet-induced obesity on acute pancreatitis induced by administration of interleukin-12 plus interleukin-18 in mice

Obesity is associated with increased severity of acute pancreatitis (AP). We recently developed a model of AP induced by administration of interleukin (IL)-12+IL-18, two cytokines that are elevated in patients with AP. In this model, severe AP develops in obese leptin-deficient ob/ob mice compared to lean littermates. In the present report, we evaluated the pancreatic response of diet-induced obesity (DIO) mice to IL-12+IL-18. Body weight loss and adipose tissue necrosis were more severe and prolonged in cytokine-injected DIO compared to lean mice. Edematous AP developed in lean mice, whereas DIO mice developed necrotizing AP. Obese DIO mice developed more severe hypocalcemia, increased liver damage and a heightened acute-phase response compared to lean mice, although leukopenia and thrombocytopenia were of comparable severity in lean and DIO mice. Serum levels of IL-6, IL-10, and IL-22 were significantly higher in DIO compared to lean mice, whereas interferon-gamma and tumor necrosis factor-alpha did not differ between the two groups. In conclusion, obesity induced by high-fat diet is associated with increased disease severity and duration in the model of AP induced by administration of IL-12+IL-18.

Adiponectin action from head to toe

Adiponectin, the most abundant protein secreted by white adipose tissue, is known for its involvement in obesity-related disorders such as insulin resistance, type 2 diabetes mellitus and atherosclerosis. Moreover, modulation of the circulating adiponectin concentration is observed in pathologies that are more or less obesity-related, such as cancer and rheumatoid arthritis. The wide distribution of adiponectin receptors in various organs and tissues suggests that adiponectin has pleiotropic effects on numerous physiological processes. Besides its well-known insulin-sensitizing, anti-inflammatory and antiatherosclerotic properties, accumulating evidence suggests that adiponectin may also have anticancer properties and be cardioprotective. A beneficial effect of adiponectin on female reproductive function was also suggested. Since adiponectin has numerous beneficial biological functions, its use as a therapeutic agent has been suggested. However, the use of adiponectin or its receptors as therapeutic targets is complicated by the presence of different adiponectin oligomeric isoforms and production sites, by multiple receptors with differing affinities for adiponectin isoforms, and by cell-type-specific effects in different tissues. In this review, we discuss the known and potential roles of adiponectin in various tissues and pathologies. The therapeutic promise of administration of adiponectin and the use of its circulating levels as a diagnostic biomarker are further discussed based on the latest experimental studies.

Experimental evidence of obesity as a risk factor for severe acute pancreatitis

The incidence of acute pancreatitis, an inflammation of the pancreas, is increasing worldwide. Pancreatic injury is mild in 80%-90% of patients who recover without complications. The remaining patients may develop a severe disease with local complications such as acinar cell necrosis, abscess and remote organ injury including lung injury. The early prediction of the severity of the disease is an important goal for physicians in management of patients with acute pancreatitis in order to optimize the therapy and to prevent organ dysfunction and local complications. For that purpose, multiple clinical scale scores have been applied to patients with acute pancreatitis. Recently, a new problem has emerged: the increased severity of the disease in obese patients. However, the mechanisms by which obesity increases the severity of acute pancreatitis are unclear. Several hypotheses have been suggested: (1) obese patients have an increased inflammation within the pancreas; (2) obese patients have an increased accumulation of fat within and around the pancreas where necrosis is often located; (3) increase in both peri- and intra-pancreatic fat and inflammatory cells explain the high incidence of pancreatic inflammation and necrosis in obese patients; (4) hepatic dysfunction associated with obesity might enhance the systemic inflammatory response by altering the detoxification of inflammatory mediators; and (5) ventilation/perfusion mismatch leading to hypoxia associated with a low pancreatic flow might reduce the pancreatic oxygenation and further enhance pancreatic injury. Recent experimental investigations also show an increased mortality and morbidity in obese rodents with acute pancreatitis and the implication of the adipokines leptin and adiponectin. Such models are important to investigate whether the inflammatory response of the disease is enhanced by obesity. It is exciting to speculate that manipulation of the adipokine milieu has the potential to influence the severity of acute pancreatitis.

Enhanced production of IL-17A during zymosan-induced peritonitis in obese mice

IL-17A is a proinflammatory cytokine critical for host defense and involved in the pathogenesis of autoimmune disorders. Obesity is associated with chronic low-grade inflammation but also with a heightened acute inflammatory response. We investigated the effect of obesity on IL-17A production using the model of ZY-induced peritonitis. Compared with lean controls, administration of ZY induced a significantly exacerbated inflammatory response in obese leptin-deficient ob/ob mice and in mice with diet-induced obesity (DIO). Levels of IL-17A in the peritoneal fluid in response to ZY were elevated significantly in ob/ob and DIO mice compared with lean animals. Reconstitution of ob/ob mice with exogenous leptin did not alter production of IL-17A significantly in response to ZY. Peritoneal cells and adipose tissue obtained from ZY-injected obese mice expressed significantly higher levels of IL-17A mRNA compared with lean mice. Approximately 2% of peritoneal Ly6G(+) neutrophils from ZY-injected obese mice expressed IL-17A protein, compared with 0.2% of cells obtained from lean mice. Neutralization of IL-17 in ob/ob mice inhibited neutrophil recruitment and production of neutrophil-attracting CXC chemokines and IL-6, without affecting macrophage infiltration or levels of IL-10 and the chemokine CCL2. In contrast, neutralization of IL-6 did not affect production of IL-17A or chemokines while reducing production of the acute-phase protein serum amyloid A significantly. These data demonstrate that neutrophil-derived IL-17A is increased in obese mice during acute inflammation and contributes to exacerbation of inflammatory responses.

Obesity potentiates the growth and dissemination of pancreatic cancer

BACKGROUND

Obesity is an independent risk factor for pancreatic cancer development and progression, although the mechanisms underlying this association are completely unknown. The aim of the current study was to investigate the influence of obesity on pancreatic cancer growth using a novel in vivo model.

METHODS

Lean (C57BL/6 J) and obese (Lep(Db) and Lep(Ob)) mice were inoculated with murine pancreatic cancer cells (PAN02), and studied after 5 weeks of tumor growth. Tumor histology was evaluated by hematoxylin and eosin staining, cellular proliferation was assessed by 5-bromodeoxyuridine, and apoptosis was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. Serum adiponectin, leptin, and insulin levels were assayed.

RESULTS

Obese mice developed larger tumors, and a significantly greater number of mice developed metastases; mortality was also greater in obese mice. Tumor apoptosis did not differ among strains, but tumors from both obese strains had greater proliferation relative to those growing in lean animals. Serum adiponectin concentration correlated negatively and serum insulin concentration correlated positively with tumor proliferation. Intratumoral adipocyte mass in tumors from both obese strains was significantly greater than that in tumors of lean mice.

CONCLUSION

Data from this novel in vivo model suggest that the altered adipokine milieu and insulin resistance observed in obesity may lead directly to changes in tumor microenvironment, thereby promoting pancreatic cancer growth and dissemination.

Nuclear magnetic resonance spectroscopy-based metabolomics of the fatty pancreas: implicating fat in pancreatic pathology

BACKGROUND

Obesity is a worldwide epidemic and a significant risk factor for pancreatic diseases including pancreatitis and pancreatic cancer; the mechanisms underlying this association are unknown. Metabolomics is a powerful new analytical approach for describing the metabolome (compliment of small molecules) of cells, tissue or biofluids at any given time. Our aim was to analyze pancreatic fat content in lean and congenitally obese mice using both metabolomic analysis and conventional chromatography.

METHODS

The pancreatic fat content of 12 lean (C57BL/6J), 12 obese leptin-deficient (Lep(ob)) and 12 obese hyperleptinemic (Lep(db)) mice was evaluated by metabolomic analysis, thin-layer and gas chromatography.

RESULTS

Pancreata of congenitally obese mice had significantly more total pancreatic fat, triglycerides and free fatty acids, but significantly less phospholipids and cholesterol than those of lean mice. Metabolomic analysis showed excellent correlation with thin-layer and gas chromatography in measuring total fat, triglycerides and phospholipids.

CONCLUSIONS

Differences in pancreatic fat content and character may have important implications when considering the local pancreatic proinflammatory milieu in obesity. Metabolomic analysis is a valid, powerful tool with which to further define the mechanisms by which fat impacts pancreatic disease.

Cannabinoid receptor-1 blockade attenuates acute pancreatitis in obesity by an adiponectin mediated mechanism

BACKGROUND

Obesity is a risk factor for increased severity of acute pancreatitis. Adipocytes produce adiponectin, an anti-inflammatory molecule that is paradoxically decreased in the setting of obesity. We have shown that adiponectin concentration inversely mirrors the severity of pancreatitis in obese mice. Cannabinoid receptor CB-1 blockade increases circulating adiponectin concentration. We, therefore, hypothesize that blockade of CB-1 would increase adiponectin and attenuate pancreatitis severity.

METHODS

Forty lean (C57BL/6J) and 40 obese (Lep(Db)) mice were studied. Half of the mice in each strain received intraperitoneal injection of the CB-1 antagonist rimonabant (10 mg/kg daily for 7 days); the others received vehicle. Pancreatitis was induced by intraperitoneal injection of cerulein (50 microg/g hourly x 6). Pancreatitis severity was determined by histology. Pancreatic chemokine and proinflammatory cytokine concentrations were measured by ELISA.

RESULTS

Rimonabant treatment significantly increased circulating adiponectin concentration in obese mice (p < 0.03 vs. vehicle). After induction of pancreatitis, obese mice treated with rimonabant had significantly decreased histologic pancreatitis (p < 0.001), significantly lower pancreatic tissue levels of monocyte chemoattractant protein-1 (p = 0.03), tumor necrosis factor-alpha (p < 0.001), interleukin-6 (p < 0.001), and myeloperoxidase (p = 0.006) relative to vehicle-treated animals.

CONCLUSIONS

In obese mice, cannabinoid receptor CB-1 blockade with rimonabant attenuates the severity of acute pancreatitis by an adiponectin-mediated mechanism.

Three questions about leptin and immunity

Leptin is a protein produced by adipocytes (and other cell types) that acts in the brain to regulate appetite and energy expenditure according to the amount of energy stored in adipose tissue. Leptin also exerts a variety of other functions, including important roles as a regulator of immune and inflammatory reactions. The present article is not meant to be a comprehensive review on leptin and immunity, but rather highlights a few controversial issues about leptin's place in the complex network of mediators regulating immune and inflammatory responses. Three issues are discussed: (1) Where am I going, or What is the cellular target of leptin for modulation of immune responses?; (2) Where am I coming from, or Is the cellular source important in determining leptin's effects on immune responses? and (3) What am I doing, or What are leptin's effects on immune and inflammatory responses?