The inverse relationship between blood amylase and insulin levels in pigs during development, bariatric surgery, and intravenous infusion of amylase

Amylase and lipase levels in the metabolic syndrome and type 2 diabetes: A longitudinal study in rhesus monkeys

Latent associations between low serum amylase and reduced plasma insulin levels and increased adiposity have been described previously in a small study of asymptomatic middle-aged humans. In the present study, we sought to determine the nature of such changes during the longitudinal progression from metabolically normal to overt type 2 diabetes mellitus (T2DM) in nonhuman primates (NHPs), a disease that appears to be the same in both pathophysiology and underlying mechanisms as that which most commonly develops in middle-aged adult humans. Amylase and lipase levels were characterized in 157 unrelated adult rhesus monkeys (Macaca mulatta); 38% developed T2DM while under study. In all monkeys, multivariable linear regression analysis revealed that amylase could be negatively predicted by % body fat (β -0.29; p = 0.002), age (β -0.27; p = 0.005), and HbA1c (β -0.18; p = 0.037). Amylase levels were positively predicted by lipase levels (β = 0.19; p = -0.024) in all NHPs included in the study. Amylase was significantly lower in NHPs with metabolic syndrome (p < 0.001), prediabetes (PreDM) (p < 0.001), and T2DM (p < 0.001) compared to metabolically normal adult NHPs. Lipase increased in NHPs with PreDM (p = 0.005) and T2DM (p = 0.04) compared to normal NHPs. This is the first longitudinal study of any species, including humans, to show the dynamics of amylase and lipase during the metabolic progression from normal to metabolic syndrome, to PreDM and then to overt T2DM. The extraordinary similarity between humans and monkeys in T2DM, in pancreatic pathophysiology and in metabolic functions give these findings high translational value.

The Modulation of Euglycemic Endocrine and Exocrine Pancreatic Secretions in Iron Deficiency

OBJECTIVES

The contribution of pancreatic secretions in iron metabolism has been elucidated, but the clinical outcomes of iron deficiency on pancreatic function are debatable. This study aimed to investigate the modulation of euglycemic endocrine and exocrine pancreatic excretions in response to variations in iron availability.

SUBJECTS AND METHODS

Serum levels of insulin, glucagon, insulin-to-glucagon ratio (IGR), and amylase were determined in 170 adult subjects with variable levels of serum iron.

RESULTS

Control (n = 46) and iron-deficient (n = 124) subjects had significant differences (p < 0.001) in their average levels of insulin (68.7 ± 0.5 vs. 100.0 ± 2.0 pmol/dL), glucagon (17.9 ± 0.6 vs. 10.8 ± 0.8 pmol/dL), IGR (4.0 ± 0.1 vs. 19.5 ± 2.1), and amylase (29.7 ± 0.9 vs. 17.5 ± 0.2). The upregulation of serum insulin levels increases proportionally and gradually to the extent of iron deficiency as compared to an abrupt downregulation of serum levels of glucagon and amylase. A significant association was observed between serum iron and IGR (r = -0.645, p < 0.001) and amylase levels (r = 0.653, p < 0.001). The receiver operating characteristic curve analysis defines an excellent predictivity of the reduced serum iron level to discriminate subjects with upregulated IGR and amylase levels with area under curves of 0.938 and 0.905, respectively.

CONCLUSION

Iron deficiency is associated with an adaptive modulation of euglycemic endocrine and exocrine secretions that is consistent with a status of insulin resistance.

Anti-Incretin Gut Features Induced by Feed Supplementation with Alpha-Amylase: Studies on EPI Pigs

The acini-islet-acinar (AIA) axis concept justifies the anatomical placement of the Langerhans islets within the exocrine pancreatic parenchyma and explains the existence of the pancreas as a single organ. Amylase has been suggested to play a key role as an anti-incretin factor. Oral glucose tolerance tests (OGTT) were performed on 18 piglets in both a healthy (prior to pancreatic duct ligation (PDL) surgery, study Day 10) and an exocrine pancreatic insufficient (EPI) state (30 days after PDL, study Day 48)). Amylase (4000 units/feeding) or Creon® (100,000 units/feeding) was administered to pigs with the morning and evening meals, according to study design randomization, for 37 days following the first OGTT. Blood glucose levels, as well as plasma levels of insulin, GLP-1, and GIP, were measured, and the HOMA-IR index was calculated. EPI status did not affect the area under the curve (AUC) of insulin release, fasting insulin levels, or the HOMA-IR index, while amylase supplementation led to a significant (p < 0.05) decrease in the above-mentioned parameters. At the same time, EPI led to a significant (p < 0.05) increase in GLP-1 levels, and neither amylase nor Creon® supplementation had any effects on this EPI-related increase. Fasting plasma levels of GIP were not affected by EPI; however, the GIP response in EPI and Amylase-treated EPI animals was significantly lower (p < 0.05) when compared to that of the intact, healthy pigs. Orally administered amylase induces gut anti-incretin action, normalizing glucose homeostasis and reducing HOMA-IR as a long-term outcome, thus lowering the risk of diabetes type II development. Amylase has long-lasting anti-incretin effects, and one could consider the existence of a long-lasting gut memory for amylase, which decreases hyperinsulinemia and hyperglycemia for up to 16 h after the last exposure of the gut to amylase.

Hypothesis that alpha-amylase evokes regulatory mechanisms originating in the pancreas, gut and circulation, which govern glucose/insulin homeostasis

The anti-incretin theory involving the abolishment of diabetes type (DT) II by some of methods used in bariatric surgery, first appeared during the early years of the XXI century and considers the existence of anti-incretin substances. However, to date no exogenous or endogenous anti-incretins have been found. Our concept of the acini-islet-acinar axis assumes that insulin intra-pancreatically stimulates alpha-amylase synthesis ("halo phenomenon") and in turn, alpha-amylase reciprocally inhibits insulin production, thus making alpha-amylase a candidate for being an anti-incretin. Additionally, gut as well as plasma alpha-amylase, of pancreatic and other origins, inhibits the appearance of dietary glucose in the blood, lowering the glucose peak after iv or oral glucose loading. This effect of alpha-amylase can be interpreted as an insulin down regulatory mechanism, possibly limiting the depletion of pancreatic beta cells and preventing their failure. Clinical observations agree with the above statements, where patients with high blood alpha-amylase concentrations are seldom obese and seldom develop DT2. Obese-DT2, as well as DT1 patients, usually develop exo-crine pancreatic insufficiency (EPI) and vice versa. Ultimately, DT2 patients develop DT1, when the pancreatic beta cells are exhausted and insulin production ceases. Studies on biliopancreatic diversion (BPD) and on BPD with duodenal switch, a type of bariatric surgery, as well as studies on EPI pigs, allow us to observe and investigate the above-mentioned phenomena of intra-pancreatic interactions.

Relationship between Body Composition and Biochemical Parameters with Antioxidant Status in a Healthy Cohort of Postmenopausal Women

An adequate prooxidant–antioxidant balance—which may be influenced by body composition and biochemical status—is essential to maintain human health, especially in circumstances under which the antioxidant defense decreases, such as menopause. The present study aimed to examine the relationship between body composition and biochemical parameters with antioxidant status in a healthy cohort of postmenopausal women. This cross-sectional study was carried out in a cohort of 78 postmenopausal women aged 44–76 years. The body composition profile was assessed through bioelectrical impedance. The determination of the total antioxidant capacity and superoxide dismutase activity was conducted by the colorimetric method, and glutathione peroxidase activity was determined by the enzymatic immunological method. The vitamin D levels were measured by ultra-performance liquid chromatography–tandem mass spectrometry. The mineral status was assessed through flame atomic absorption spectrophotometry. The rest of the biochemical parameters were assessed through an immunoassay. The total antioxidant capacity and antioxidant gap were negatively influenced by body composition (all p ≤ 0.049) and positively related to protein metabolism parameters (all p ≤ 0.048), whereas circulating levels of different micronutrients (all p ≤ 0.048) and enzymes (all p ≤ 0.047) appeared to play an important role in the glutathione peroxidase and superoxide dismutase activities. In conclusion, the menopause-related antioxidant status changes may be influenced by key body composition and biochemical profiles. To confirm this statement, further trials aiming to evaluate the body composition and biochemical intervention-induced changes upon antioxidant defense are needed.

Alpha-Amylase Inhibits Cell Proliferation and Glucose Uptake in Human Neuroblastoma Cell Lines

The present article describes a study of the effects of alpha-amylase (α-amylase) on the human neuroblastoma (NB) cell lines SH-SY5Y, IMR-32, and LA-N-1. NB is the most common malignancy diagnosed in infants younger than 12 months. Some clinical observations revealed an inverse association between the risk of NB development and breastfeeding. α-Amylase which is present in breast milk was shown to have anticancer properties already in the beginning of the 20th century. Data presented here show that pancreatic α-amylase inhibits cell proliferation and has a direct impact on glucose uptake in the human NB cell lines. Our results point out the importance of further research which could elucidate the α-amylase mode of action and justify the presence of this enzyme in breast milk as a possible inhibitor of NB development. α-Amylase can be thus recognized as a potential safe and natural mild/host anticancer agent minimizing chemotherapy-related toxicity in the treatment of NB.

Effects of hypothyroidism on the female pancreas involve the regulation of estrogen receptors

This study aimed to investigate the impact of short-time hypothyroidism on the expression of aromatase, estrogen receptors (ERα, β), and GPR30 in the pancreas of female rabbits. The formation of new islets and the expression of insulin, GLUT4, and lactate dehydrogenase (LDH) were also analyzed. This purpose is based on actions that thyroid hormones and estrogens have on β-cells differentiation, acinar cell function, and insulin secretion. Twelve Chinchilla-breed adult virgin female rabbits were divided into control (n = 6) and hypothyroid (n = 6; methimazole 10 mg/kg for 30 days) groups. In the complete pancreas, expressions of aromatase and estrogen receptors, as well as proinsulin, GLUT4, and LDH were determined by western blot. Characteristics of islets were measured in slices of the pancreas with immunohistochemistry for insulin. Islet and acinar cells express aromatase, ERα, ERβ, and GPR30. Hypothyroidism increased the expression of ERα and diminished that for aromatase, ERβ, and GPR30 in the pancreas. It also promoted a high number of extra small islets (new islets) and increased the expression of proinsulin and GLUT4 in the pancreas. Our results show that actions of thyroid hormones and estrogens on β-cells neogenesis, acinar cell function, and synthesis and secretion of insulin are linked. Thus, the effects of hypothyroidism on the pancreas could include summatory actions of thyroid hormones plus estrogens. Our findings indicate the importance of monitoring estrogen levels and actions on the pancreas of hypothyroid women, particularly when serum estrogen concentrations are affected such as menopausal, pregnant, and those with contraceptive use.

Schiff Bases of Pioglitazone Provide Better Antidiabetic and Potent Antioxidant Effect in a Streptozotocin-Nicotinamide-Induced Diabetic Rodent Model

Pioglitazone is a Food and Drug Administration-approved thiazolidinedione (TZD) derivative and peroxisome proliferator-activated receptor gamma (PPARγ) agonist and used for the treatment of diabetes mellitus (DM). However, this drug is still associated with many adverse effects. In the present study, four new Schiff bases of pioglitazone (P1-P4) were synthesized and characterized using FTIR, ¹HNMR, ¹³CNMR, mass spectrometry, and elemental analysis. For preliminary screening, the in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and in vitro alpha-amylase antidiabetic inhibitory assay were performed. Further, P3 was used to investigate in vivo antioxidant and in vivo antidiabetic effects in a streptozotocin-nicotinamide-induced diabetic rat model. Diabetic rats were administered with an i.p dose of pioglitazone 10 mg/kg body weight for 21 days. Moreover, biochemical parameters and antioxidants were quantified from liver and kidney tissues of rodents. In the DPPH assay, compound P3 showed superior antioxidant effects. Using the in vitro α-amylase inhibitory assay, P3 exhibited potent effects as compared to other groups, that is, 93% inhibition, while pioglitazone showed 81% inhibition. Enzymatic and nonenzymatic antioxidants showed significant changes in P3 (10 mg/kg)-treated groups (p < 0.001). Similarly, compound P3 produced significant and better results in comparison to pioglitazone in the rodent model. This study confirmed potent antidiabetic and superior antioxidant potential of the newly synthesized Schiff base (P3), which could ultimately account for insulin sensitization and for cellular protection and hence provide a potential clue for dual therapeutics.

Effect of Bariatric Surgery on Serum Enzyme Status in Obese Patients

BACKGROUND

Scarce data exists about serum enzyme in bariatric patients. We attempted to evaluate serum enzyme status in patients receiving Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) and to identify related predictors.

METHODS

We retrospectively reviewed the patients receiving RYGB and SG in our center from January 2013 to January 2018. Anthropometric data and serum enzyme data were collected preoperatively and 6 and 12 months postoperatively.

RESULTS

Five hundred patients (201 RYGB, 299 SG) were included. Serum enzyme abnormalities were common preoperatively, with 50.8% for elevated alanine aminotransferase (ALT), 33.0% for elevated aspartate aminotransferase (AST), 36.6% for elevated γ-glutamyltranspeptidase (γ-GT), 17.6% for elevated creatine kinase (CK), 15.2% for elevated lactic dehydrogenase (LDH), 9.0% for elevated adenosine deaminase (ADA), 6.2% for elevated hydroxybutyrate dehydrogenase (HBDH), and 8.4% for decreased superoxide dismutase (SOD). After RYGB and SG, the prevalence of serum ALT, AST, γ-GT, LDH, and HBDH abnormalities reduced. The levels of ALT, AST, γ-GT, ADA, cholinesterase (CHE), LDH, CK, and HBDH reduced significantly, while amylase and SOD levels increased. Age and preoperative γ-GT level were independent predictors of ALT, AST, γ-GT, and LDH change 1 year postoperatively. Preoperative ALT, AST, ALP, LDH, and HBDH levels could predict postoperative change, respectively. Gender and surgical procedure could predict postoperative ALP change.

CONCLUSION

Serum enzyme abnormalities are common in bariatric surgery candidates, with reduced prevalence of abnormalities postoperatively. RYGB and SG are related with reduced ALT, AST, γ-GT, ADA, CHE, LDH, CK, and HBDH levels, as well as increased amylase and SOD levels.

Amylase-Dependent Regulation of Glucose Metabolism and Insulin/Glucagon Secretion in the Streptozotocin-Induced Diabetic Pig Model and in a Rat Pancreatic Beta-Cell Line, BRIN-BD11

The current study was aimed at highlighting the role of blood pancreatic amylase in the regulation of glucose homeostasis and insulin secretion in a porcine model of streptozotocin- (STZ-) induced diabetes and in a rat pancreatic beta-cell line, BRIN-BD11. Blood glucose, plasma insulin, and glucagon levels were measured following a duodenal glucose tolerance test (IDGTT), in four pigs with STZ-induced type 2 diabetes (T2D pigs) and in four pigs with STZ-induced type 1 diabetes (T1D pigs). Four intact pigs were used as the control group. The effect of amylase supplementation on both acute and chronic insulin secretion was determined in a BRIN-BD11 cell line. The amylase infusion had no effect on the glucose utilization curve or glucagon levels in the healthy pigs. However, a significant lowering of insulin release was observed in healthy pigs treated with amylase. In the T2D pigs, the glucose utilization curve was significantly lowered in the presence of amylase, while the insulin response curve remained unchanged. Amylase also significantly increased glucagon release during the IDGTT in the T2D and T1D pigs, by between 2- and 4-fold. Amylase did not affect the glucose utilization curve in the T1D pigs. Amylase supplementation significantly decreased both acute and chronic insulin secretion in the BRIN-BD11 cells. These data confirm our previous observations and demonstrate the participation of pancreatic amylase in glucose absorption/utilization. Moreover, the present study clearly highlights the direct impact of pancreatic blood amylase on insulin secretion from pancreatic beta-cells and its interactions with insulin and glucagon secretion in a porcine model.

Glucose homeostasis dependency on acini-islet-acinar (AIA) axis communication: a new possible pathophysiological hypothesis regarding diabetes mellitus

Studies have highlighted the existence of two intra-pancreatic axes of communication: one involved in the regulation of enzyme production by insulin-the insular-acinar axis; and another involved in the regulation of insulin release by pancreatic enzymes-the acini-insular axis. Previous studies by our laboratory show that pancreatic enzymes can affect blood glucose homeostasis and insulin secretion independently of their digestive functions, both from the gut lumen and probably from the blood. As a result we would like to introduce here the concept of acini-islet-acinar (AIA) axis communication (feedback), which could play an important role in the development of obesity and diabetes type 2. The AIA feedback links the endocrine and exocrine parts of the pancreas and emphasizes the essential role that the pancreas plays, as a single organ, in the regulation of glucose homeostasis by amylase most probably in gut epithelium and by insulin and glucagon in peripheral blood.

Activation of mTORC1 signaling in gastric X/A-like cells induces spontaneous pancreatic fibrosis and derangement of glucose metabolism by reducing ghrelin production

BACKGROUND

Pancreatic fibrosis is a pathophysiological process associated with excessive deposition of extracellular matrix in pancreas, leading to reduced insulin secretion and derangement of glucose metabolism. X/A-like cells, a group of unique endocrine cells in gastric oxyntic mucosa, produce and secret ghrelin to influence energy balance. Whether gastric X/A-like cells affect pancreatic fibrosis and subsequent glucose homeostasis remains unclear.

METHODS

We established a Ghrl-cre transgene in which the cre enzyme is expressed in X/A-like cells under the control of ghrelin-promoter. TSC1flox/flox mice were bred with Ghrl-cre mice to generate Ghrl-TSC1-/- (TG) mice, within which mTORC1 signaling was activated in X/A-like cells. Pancreatic fibrosis and insulin secretion were analyzed in the TG mice.

FINDINGS

Activation of mTORC1 signaling by deletion of TSC1 gene in gastric X/A-like cells induced spontaneous pancreatic fibrosis. This alteration was associated with reduced insulin expression and secretion, as well as impaired glucose metabolism. Activation of mTORC1 signaling in gastric X/A-like cells reduced gastric and circulating ghrelin levels. Exogenous ghrelin reversed pancreatic fibrosis and glucose intolerance induced by activation of mTORC1 signaling in these cells. Rapamycin, an inhibitor of mTOR, reversed the decrease of ghrelin levels and pancreatic fibrosis.

INTERPRETATION

Activation of mTORC1 signaling in gastric X/A-like cells induces spontaneous pancreatic fibrosis and subsequently impairs glucose homeostasis via suppression of ghrelin.