Obesity-induced pancreatopathy in rats is reversible after bariatric surgery

Acinar-to-Ductal Metaplasia (ADM): On the Road to Pancreatic Intraepithelial Neoplasia (PanIN) and Pancreatic Cancer

Adult pancreatic acinar cells show high plasticity allowing them to change in their differentiation commitment. Pancreatic acinar-to-ductal metaplasia (ADM) is a cellular process in which the differentiated pancreatic acinar cells transform into duct-like cells. This process can occur as a result of cellular injury or inflammation in the pancreas. While ADM is a reversible process allowing pancreatic acinar regeneration, persistent inflammation or injury can lead to the development of pancreatic intraepithelial neoplasia (PanIN), which is a common precancerous lesion that precedes pancreatic ductal adenocarcinoma (PDAC). Several factors can contribute to the development of ADM and PanIN, including environmental factors such as obesity, chronic inflammation and genetic mutations. ADM is driven by extrinsic and intrinsic signaling. Here, we review the current knowledge on the cellular and molecular biology of ADM. Understanding the cellular and molecular mechanisms underlying ADM is critical for the development of new therapeutic strategies for pancreatitis and PDAC. Identifying the intermediate states and key molecules that regulate ADM initiation, maintenance and progression may help the development of novel preventive strategies for PDAC.

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

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

Increased Galactosidase Beta 1 Expression as a Senescent Key Factor in β-Cells Function Modulation at the Early Steps of Type 2 Diabetes

BACKGROUND

In type 2 diabetes, insulin resistance is observed, and β-cells are incapable of responding to glycemia demands, leading to hyperglycemia. Although the nature of β-cells dysfunction in this disease is not fully understood, a link between the induction of pancreatic β-cell premature senescence and its metabolic implications has been proposed. This study aimed to understand the relationship between diabetes and pancreatic senescence, particularly at the beginning of the disease.

METHODS

C57Bl/6 J mice were fed two different diets, a normal diet and a high-fat diet, for 16 weeks. Pancreatic histomorphology analysis, insulin quantification, inflammation parameters, and senescence biomarkers for the experimental animals were assessed at weeks 12 and 16.

RESULTS

The results proved that diabetes onset occurred at week 16 in the High Fat Diet group, supported by glycaemia, weight and blood lipid levels. Increased β-cells size and number accompanied by increased insulin expression were observed. Also, an inflammatory status of the diabetic group was noted by increased levels of systemic IL-1β and increased pancreatic fibrosis. Finally, the expression of galactosidase-beta 1 (GLB1) was significantly increased in pancreatic β-cells.

CONCLUSION

The study findings indicate that senescence, as revealed by an increase in GLB1 expression, is a key factor in the initial stage of diabetes.

Hyperglycemia remission after Roux-en-Y gastric bypass: Implicated to altered monocyte inflammatory response in type 2 diabetes rats

Hyperglycemia remission by metabolic surgery is implicated in the resolution of low-grade inflammation in type 2 diabetes mellitus (T2DM). However, whether this beneficial effect of metabolic surgery is related to improving monocyte inflammatory response remains undefined. This investigation is addressed to evaluate this relationship. For this purpose, T2DM rats were subjected to Roux-en-Y gastric bypass (RYGB) and/or monocyte depletion or splenic sympathetic denervation. Fasting blood glucose (FBG), plasma tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) were measured, and monocyte inflammatory response was assessed in vitro. The data showed that RYGB significantly reduced lipopolysaccharide (LPS)-induced release of TNF-α and IL-1β from peripheral monocytes while alleviating hyperglycemia and reducing plasma TNF-α and IL-1β levels. Hyperglycemia resulting from monocyte depletion by injection of clodronate liposomes resolved one week earlier than vehicle control after RYGB. Splenic denervation abrogated the glucose-lowering effect and decreased LPS-stimulated TNF-α and IL-1β release from monocytes following RYGB. Overall, our results reveal that a marked reduction of monocyte inflammatory response after RYGB contributes to hyperglycemia remission in T2DM rats. The beneficial effect of RYGB is mediated through vagal-spleen axis anti-inflammatory activity.

Uniting epidemiology and experimental models: pancreatic steatosis and pancreatic cancer

Research from epidemiologic studies and experimental animal models provide insights into the role of pancreatic steatosis in the development of pancreatic cancer. Epidemiologic data demonstrate that pancreatic steatosis is widely prevalent and significantly associated with both development and progression of pancreatic cancer. By focusing on current experimental models, this review elucidates potential cellular mechanisms underlying not only the pathophysiology of pancreatic steatosis itself, but also the pathogenesis behind pancreatic steatosis's role in changing the tumour microenvironment and accelerating the development of pancreatic cancer. This review further explores the impact of bariatric surgery on pancreatic steatosis and pancreatic cancer. Synthesizing knowledge from both epidemiologic studies and experimental animal models, this review identifies gaps in current knowledge regarding pancreatic steatosis and its role in carcinogenesis and proposes future research directions to elucidate the possible mechanisms underlying other obesity-associated cancers.

Necro-inflammatory activity grading in chronic viral hepatitis with three-dimensional multifrequency MR elastography

The purpose of this study was to assess the diagnostic value of multifrequency MR elastography for grading necro-inflammation in the liver. Fifty participants with chronic hepatitis B or C were recruited for this institutional review board-approved study. Their liver was examined with multifrequency MR elastography. The storage, shear and loss moduli, and the damping ratio were measured at 56 Hz. The multifrequency wave dispersion coefficient of the shear modulus was calculated. The measurements were compared to reference markers of necro-inflammation and fibrosis with Spearman correlations and multiple regression analysis. Diagnostic accuracy was assessed. At multiple regression analysis, necro-inflammation was the only determinant of the multifrequency dispersion coefficient, whereas fibrosis was the only determinant of the storage, loss and shear moduli. The multifrequency dispersion coefficient had the largest AUC for necro-inflammatory activity A ≥ 2 [0.84 (0.71–0.93) vs. storage modulus AUC: 0.65 (0.50–0.79), p = 0.03], whereas the storage modulus had the largest AUC for fibrosis F ≥ 2 [AUC (95% confidence intervals) 0.91 (0.79–0.98)] and cirrhosis F4 [0.97 (0.88–1.00)]. The measurement of the multifrequency dispersion coefficient at three-dimensional MR elastography has the potential to grade liver necro-inflammation in patients with chronic vial hepatitis.

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.

Potential metabolic resistance mechanisms to ivermectin in Anopheles gambiae: a synergist bioassay study

Background

Despite remarkable success obtained with current malaria vector control strategies in the last 15 years, additional innovative measures will be needed to achieve the ambitious goals for malaria control set for 2030 by the World Health Organization (WHO). New tools will need to address insecticide resistance and residual transmission as key challenges. Endectocides such as ivermectin are drugs that kill mosquitoes which feed on treated subjects. Mass administration of ivermectin can effectively target outdoor and early biting vectors, complementing the still effective conventional tools. Although this approach has garnered attention, development of ivermectin resistance is a potential pitfall. Herein, we evaluate the potential role of xenobiotic pumps and cytochrome P450 enzymes in protecting mosquitoes against ivermectin by active efflux and metabolic detoxification, respectively.

Methods

We determined the lethal concentration 50 for ivermectin in colonized Anopheles gambiae; then we used chemical inhibitors and inducers of xenobiotic pumps and cytochrome P450 enzymes in combination with ivermectin to probe the mechanism of ivermectin detoxification.

Results

Dual inhibition of xenobiotic pumps and cytochromes was found to have a synergistic effect with ivermectin, greatly increasing mosquito mortality. Inhibition of xenobiotic pumps alone had no effect on ivermectin-induced mortality. Induction of xenobiotic pumps and cytochromes may confer partial protection from ivermectin.

Conclusion

There is a clear pathway for development of ivermectin resistance in malaria vectors. Detoxification mechanisms mediated by cytochrome P450 enzymes are more important than xenobiotic pumps in protecting mosquitoes against ivermectin.

MR elastography: Principles, guidelines, and terminology

Magnetic resonance elastography (MRE) is a phase contrast-based MRI technique that can measure displacement due to propagating mechanical waves, from which material properties such as shear modulus can be calculated. Magnetic resonance elastography can be thought of as quantitative, noninvasive palpation. It is increasing in clinical importance, has become widespread in the diagnosis and staging of liver fibrosis, and additional clinical applications are being explored. However, publications have reported MRE results using many different parameters, acquisition techniques, processing methods, and varied nomenclature. The diversity of terminology can lead to confusion (particularly among clinicians) about the meaning of and interpretation of MRE results. This paper was written by the MRE Guidelines Committee, a group formalized at the first meeting of the ISMRM MRE Study Group, to clarify and move toward standardization of MRE nomenclature. The purpose of this paper is to (1) explain MRE terminology and concepts to those not familiar with them, (2) define "good practices" for practitioners of MRE, and (3) identify opportunities to standardize terminology, to avoid confusion.

Iron Metabolism in Obesity and Metabolic Syndrome

Obesity is an excessive adipose tissue accumulation that may have detrimental effects on health. Particularly, childhood obesity has become one of the main public health problems in the 21st century, since its prevalence has widely increased in recent years. Childhood obesity is intimately related to the development of several comorbidities such as nonalcoholic fatty liver disease, dyslipidemia, type 2 diabetes mellitus, non-congenital cardiovascular disease, chronic inflammation and anemia, among others. Within this tangled interplay between these comorbidities and associated pathological conditions, obesity has been closely linked to important perturbations in iron metabolism. Iron is the second most abundant metal on Earth, but its bioavailability is hampered by its ability to form highly insoluble oxides, with iron deficiency being the most common nutritional disorder. Although every living organism requires iron, it may also cause toxic oxygen damage by generating oxygen free radicals through the Fenton reaction. Thus, iron homeostasis and metabolism must be tightly regulated in humans at every level (i.e., absorption, storage, transport, recycling). Dysregulation of any step involved in iron metabolism may lead to iron deficiencies and, eventually, to the anemic state related to obesity. In this review article, we summarize the existent evidence on the role of the most recently described components of iron metabolism and their alterations in obesity.

Pancreatic Steatosis: An Emerging Clinical Entity

Pancreatic steatosis is an emerging clinical entity whose pathophysiology, natural history, and long-term complications are poorly characterized in the current literature. Epidemiological and prospective studies have described prevalence rates between 16% and 35%. Although the natural history is not well known, there are strong associations with obesity, metabolic syndrome, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. Ectopic fat accumulation of the pancreas can cause chronic, low-grade inflammation from adipocytokine imbalances that involve beta cells and acinar cells. This mechanism can lead to pancreatic endocrine and exocrine dysfunction and initiate carcinogenesis. Although it is associated with morbid conditions, pancreatic steatosis may be amendable to treatment with a healthy diet, less meat consumption, exercise, and smoking cessation. Pancreatic steatosis should factor into clinical decision-making and prognostication of patients with pancreatic and systemic disease. This review seeks to describe the pathophysiology, natural history, diagnosis, and complications of this emerging clinically relevant entity.

Effect of different bariatric surgeries on dietary protein bioavailability in rats

Bariatric surgery may induce protein malabsorption, although data are scarce. This study aims at evaluating dietary protein bioavailability after different bariatric surgeries in rats. Diet-induced obese Wistar rats were operated for vertical sleeve gastrectomy (VSG) or Roux-en-Y gastric bypass (RYGB). The control group was composed of pair-fed, sham-operated rats (Sham). Two weeks after surgery, rats were fed a ¹⁵N protein meal. Protein bioavailability was assessed by determination of ¹⁵N recovery in the gastrointestinal tract and organs 6 h after the meal. Fractional protein synthesis rate (FSR) was assessed using a flooding dose of ¹³C valine. Weight loss was the highest in RYGB rats and the lowest in Sham rats. Surprisingly, RYGB (95.6 ± 0.7%) improved protein digestibility (P = 0.045) compared with Sham (93.5 ± 0.5%) and VSG (93.8 ± 0.6%). In contrast, ¹⁵N retained in the liver (P = 0.001) and plasma protein (P = 0.037) was lower than in Sham, with a similar trend in muscle (P = 0.052). FSR was little altered by bariatric surgery, except for a decrease in the kidney of RYGB (P = 0.02). The ¹⁵N distribution along the small intestinal tissue suggests that dietary nitrogen was considerably retained in the remodeled mucosa of RYGB compared with Sham. This study revealed that in contrast to VSG, RYGB slightly improved protein digestibility but altered peripheral protein bioavailability. This effect may be ascribed to a higher uptake of dietary amino acids by the remodeled intestine.NEW & NOTEWORTHY Using a sensitive ¹⁵N meal test, we found that gastric bypass slightly improved protein digestibility compared with sleeve gastrectomy or control but, in contrast, lowered protein retention in the liver and muscles. This paradox can be due to a higher uptake of dietary nitrogen by the intestinal mucosa that was hypertrophied. This study provides new insight on the digestive and metabolic fate of dietary protein in different models of bariatric surgery in rats.

Pancreatic steatosis: an update

PURPOSE OF REVIEW

Pancreatic steatosis is a clinical entity with emerging significance and impacts patient health in a multitude of ways. It has a high prevalence in the global population with predilections for different demographics by age, sex and ethnicity. Understanding the pathophysiology, clinical features and complications of this entity may be important to understanding the consequences of the ongoing obesity global epidemic.

RECENT FINDINGS

Obesity and metabolic syndrome contribute to metabolic derangements that result in lipid mishandling by adipocytes. Adipocytokine imbalances in circulation and in the pancreatic microenvironment cause chronic, low-grade inflammation. The resulting beta cell and acinar cell apoptosis leads to pancreatic endocrine and exocrine dysfunction. Furthermore, these adipocytokines regulate cell growth, differentiation, as well as angiogenesis and lymphatic spread. These consequences of adipocyte infiltration are thought to initiate carcinogenesis, leading to pancreatic intraepithelial neoplasia and pancreatic ductal adenocarcinoma.

SUMMARY

Obesity will lead to millions of deaths each year and pancreatic steatosis may be the key intermediate entity that leads to obesity-related complications. Enhancing our understanding may reveal strategies for preventing mortality and morbidity related to the global epidemic of obesity. Further research is needed to determine the pathophysiology, long-term complications and effective treatment strategies for this condition.