Food intake and meal pattern in IAPP knockout mice with and without infusion of exogenous IAPP

Immune and metabolic challenges induce changes in pain sensation and related pathways in the hypothalamus

The hypothalamic molecular processes participate in the regulation of the neuro-immune-endocrine system, including hormone, metabolite, chemokine circulation, and corresponding physiological and behavioral responses. RNA-sequencing profiles were analyzed to understand the effect of juvenile immune and metabolic distress 100 days after virally elicited maternal immune activation during gestation in pigs. Over 1,300 genes exhibited significant additive or interacting effects of gestational immune activation, juvenile distress, and sex. One-third of these genes presented multiple effects, emphasizing the complex interplay of these factors. Key functional categories enriched among affected genes included sensory perception of pain, steroidogenesis, prolactin, neuropeptide, and inflammatory signaling. These categories underscore the intricate relationship between gestational immune activation during gestation, distress, and the response of hypothalamic pathways to insults. These effects were sex-dependent for many genes, such as Prdm12, Oprd1, Isg20, Prl, Oxt, and Vip. The prevalence of differentially expressed genes annotated to proinflammatory and cell cycle processes suggests potential implications for synaptic plasticity and neuronal survival. The gene profiles affected by immune activation, distress, and sex pointed to the action of transcription factors SHOX2, STAT1, and REST. These findings underscore the importance of considering sex and postnatal challenges when studying causes of neurodevelopmental disorders and highlight the complexity of the "two-hit" hypothesis in understanding their etiology. Our study furthers the understanding of the intricate molecular responses in the hypothalamus to gestational immune activation and subsequent distress, shedding light on the sex-specific effects and the potential long-lasting consequences on pain perception, neuroendocrine regulation, and inflammatory processes.NEW & NOTEWORTHY The interaction of infection during gestation and insults later in life influences the molecular mechanisms in the hypothalamus that participate in pain sensation. The response of the hypothalamic transcriptome varies between sexes and can also affect synapses and immune signals. The findings from this study assist in the identification of agonists or antagonists that can guide pretranslational studies to ameliorate the effects of gestational insults interacting with postnatal challenges on physiological or behavioral disorders.

Islet amyloid polypeptide does not suppress pancreatic cancer

OBJECTIVES

Pancreatic cancer risk is elevated approximately two-fold in type 1 and type 2 diabetes. Islet amyloid polypeptide (IAPP) is an abundant beta-cell peptide hormone that declines with diabetes progression. IAPP has been reported to act as a tumour-suppressor in p53-deficient cancers capable of regressing tumour volumes. Given the decline of IAPP during diabetes development, we investigated the actions of IAPP in pancreatic ductal adenocarcinoma (PDAC; the most common form of pancreatic cancer) to determine if IAPP loss in diabetes may increase the risk of pancreatic cancer.

METHODS

PANC-1, MIA PaCa-2, and H1299 cells were treated with rodent IAPP, and the IAPP analogs pramlintide and davalintide, and assayed for changes in proliferation, death, and glycolysis. An IAPP-deficient mouse model of PDAC (Iapp^-/-; Kras^+/LSL-G12D; Trp53^flox/flox; Ptf1a^+/CreER) was generated for survival analysis.

RESULTS

IAPP did not impact glycolysis in MIA PaCa-2 cells, and did not impact cell death, proliferation, or glycolysis in PANC-1 cells or in H1299 cells, which were previously reported as IAPP-sensitive. Iapp deletion in Kras^+/LSL-G12D; Trp53^flox/flox; Ptf1a^+/CreER mice had no effect on survival time to lethal tumour burden.

CONCLUSIONS

In contrast to previous reports, we find that IAPP does not function as a tumour suppressor. This suggests that loss of IAPP signalling likely does not increase the risk of pancreatic cancer in individuals with diabetes.

Mediators of Amylin Action in Metabolic Control

Amylin (also called islet amyloid polypeptide (IAPP)) is a pancreatic beta-cell hormone that is co-secreted with insulin in response to nutrient stimuli. The last 35 years of intensive research have shown that amylin exerts important physiological effects on metabolic control. Most importantly, amylin is a physiological control of meal-ending satiation, and it limits the rate of gastric emptying and reduces the secretion of pancreatic glucagon, in particular in postprandial states. The physiological effects of amylin and its analogs are mediated by direct brain activation, with the caudal hindbrain playing the most prominent role. The clarification of the structure of amylin receptors, consisting of the calcitonin core receptor plus receptor-activity modifying proteins, aided in the development of amylin analogs with a broad pharmacological profile. The general interest in amylin physiology and pharmacology was boosted by the finding that amylin is a sensitizer to the catabolic actions of leptin. Today, amylin derived analogs are considered to be among the most promising approaches for the pharmacotherapy against obesity. At least in conjunction with insulin, amylin analogs are also considered important treatment options in diabetic patients, so that new drugs may soon be added to the only currently approved compound pramlintide (Symlin^®). This review provides a brief summary of the physiology of amylin’s mode of actions and its role in the control of the metabolism, in particular energy intake and glucose metabolism.

Mono and dual agonists of the amylin, calcitonin, and CGRP receptors and their potential in metabolic diseases

BACKGROUND

Therapies for metabolic diseases are numerous, yet improving insulin sensitivity beyond that induced by weight loss remains challenging. Therefore, search continues for novel treatment candidates that can stimulate insulin sensitivity and increase weight loss efficacy in combination with current treatment options. Calcitonin gene-related peptide (CGRP) and amylin belong to the same peptide family and have been explored as treatments for metabolic diseases. However, their full potential remains controversial.

SCOPE OF REVIEW

In this article, we introduce this rather complex peptide family and its corresponding receptors. We discuss the physiology of the peptides with a focus on metabolism and insulin sensitivity. We also thoroughly review the pharmacological potential of amylin, calcitonin, CGRP, and peptide derivatives as treatments for metabolic diseases, emphasizing their ability to increase insulin sensitivity based on preclinical and clinical studies.

MAJOR CONCLUSIONS

Amylin receptor agonists and dual amylin and calcitonin receptor agonists are relevant treatment candidates, especially because they increase insulin sensitivity while also assisting weight loss, and their unique mode of action complements incretin-based therapies. However, CGRP and its derivatives seem to have only modest if any metabolic effects and are no longer of interest as therapies for metabolic diseases.

A New Perspective in Utilizing MMP-9 as a Therapeutic Target for Alzheimer's Disease and Type 2 Diabetes Mellitus

Matrix metalloprotease 9 (MMP-9) is a 92 kDa type IV collagenase and a member of the family of endopeptidases. MMP-9 is involved in the degradation of extracellular matrix components, tissue remodeling, cellular receptor stripping, and processing of various signaling molecules. In the CNS, the effects of MMP-9 are quite complex, since it exerts beneficial effects including neurogenesis, angiogenesis, myelogenesis, axonal growth, and inhibition of apoptosis, or destructive effects including apoptosis, blood-brain barrier disorder, and demyelination. Likewise, in the periphery, physiological events, as the involvement of MMP-9 in angiogenesis, for instance in wound healing, can be turned into pathological, such as in tumor metastasis, depending on the state of the organism. Alzheimer's disease is a neurodegenerative disorder, characterized by amyloid accumulation and deposition in the brain. Amyloidogenesis, however, also occurs in diseases of the periphery, such as type II diabetes mellitus, where an analogous type of amyloid, is deposited in the pancreas. Interestingly, both diseases exhibit similar pathology and disease progression, with insulin resistance being a major common denominator. Hence, combinatorial strategies searching new or existing molecules to apply for therapeutic use for both diseases are gaining momentum. MMP-9 is extensively studied due to its association with a variety of physiological and pathological processes. Consequently, meticulous design could render MMP-9 into a potential therapeutic target for Alzheimer's disease and type 2 diabetes mellitus; two seemingly unrelated diseases.

Enzyme replacement improves survival among patients with pancreatic cancer: Results of a population based study

BACKGROUND

Pancreatic exocrine insufficiency (PEI) and malnutrition are prevalent among patients with pancreatic adenocarcinoma. Pancreatic enzyme replacement therapy (PERT) can correct PEI but its use among patients with pancreatic cancer is unclear as are effects upon survival. This population-based study sought to address these issues METHODS: Subjects with pancreatic adenocarcinoma were identified from the UK Clinical Practice Research Datalink (CPRD). Propensity score matching generated matched pairs of subjects who did and did not receive PERT. Progression to all-cause mortality was compared using parametric survival models that included a range of relevant co-variables RESULTS: PERT use among the whole cohort (987/4554) was 21.7%. Some 1614 subjects generated 807 matched pairs. This resulted in a total, censored follow-up period of 1643 years. There were 1403 deaths in total, representing unadjusted mortality rates of 748 and 994 deaths per 1000 person-years for PERT-treated cases and their matched non-PERT-treated controls, respectively. With reference to the observed survival in pancreatic adenocarcinoma patients, adjusted median survival time was 262% greater in PERT-treated cases (survival time ratio (STR) = 2.62, 95% CI 2.27-3.02) when compared with matched, non-PERT-treated controls. Survival remained significantly greater among subjects receiving PERT regardless of the studied subgroup with respect to use of surgery or chemotherapy CONCLUSIONS: This population based study observes that the majority of patients with pancreatic adenocarcinoma do not receive PERT. PERT is associated with increased survival among patients with pancreatic adenocarcinoma suggesting a lack of clinical awareness and potential benefit of addressing malnutrition among these patients.

Pancreatic Exocrine Insufficiency in Pancreatic Cancer

Abstract: Cancer patients experience weight loss for a variety of reasons, commencing with the tumor’s metabolism (Warburg effect) and proceeding via cachexia to loss of appetite. In pancreatic cancer, several other factors are involved, including a loss of appetite with a particular aversion to meat and the incapacity of the pancreatic gland to function normally when a tumor is present in the pancreatic head. Pancreatic exocrine insufficiency is characterized by a deficiency of the enzymes secreted from the pancreas due to the obstructive tumor, resulting in maldigestion. This, in turn, contributes to malnutrition, specifically a lack of fat-soluble vitamins, antioxidants, and other micronutrients. Patients with pancreatic cancer and pancreatic exocrine insufficiency have, overall, an extremely poor prognosis with regard to surgical outcome and overall survival. Therefore, it is crucial to be aware of the mechanisms involved in the disease, to be able to diagnose pancreatic exocrine insufficiency early on, and to treat malnutrition appropriately, for example, with pancreatic enzymes.

Amylin: Pharmacology, Physiology, and Clinical Potential

Amylin is a pancreatic β-cell hormone that produces effects in several different organ systems. Here, we review the literature in rodents and in humans on amylin research since its discovery as a hormone about 25 years ago. Amylin is a 37-amino-acid peptide that activates its specific receptors, which are multisubunit G protein-coupled receptors resulting from the coexpression of a core receptor protein with receptor activity-modifying proteins, resulting in multiple receptor subtypes. Amylin's major role is as a glucoregulatory hormone, and it is an important regulator of energy metabolism in health and disease. Other amylin actions have also been reported, such as on the cardiovascular system or on bone. Amylin acts principally in the circumventricular organs of the central nervous system and functionally interacts with other metabolically active hormones such as cholecystokinin, leptin, and estradiol. The amylin-based peptide, pramlintide, is used clinically to treat type 1 and type 2 diabetes. Clinical studies in obesity have shown that amylin agonists could also be useful for weight loss, especially in combination with other agents.

Amylin modulates the mesolimbic dopamine system to control energy balance

Amylin acts in the CNS to reduce feeding and body weight. Recently, the ventral tegmental area (VTA), a mesolimbic nucleus important for food intake and reward, was identified as a site-of-action mediating the anorectic effects of amylin. However, the long-term physiological relevance and mechanisms mediating the intake-suppressive effects of VTA amylin receptor (AmyR) activation are unknown. Data show that the core component of the AmyR, the calcitonin receptor (CTR), is expressed on VTA dopamine (DA) neurons and that activation of VTA AmyRs reduces phasic DA in the nucleus accumbens core (NAcC). Suppression in NAcC DA mediates VTA amylin-induced hypophagia, as combined NAcC D1/D2 receptor agonists block the intake-suppressive effects of VTA AmyR activation. Knockdown of VTA CTR via adeno-associated virus short hairpin RNA resulted in hyperphagia and exacerbated body weight gain in rats maintained on high-fat diet. Collectively, these findings show that VTA AmyR signaling controls energy balance by modulating mesolimbic DA signaling.

Gut-Brain Endocrine Axes in Weight Regulation and Obesity Pharmacotherapy

In recent years, the obesity epidemic has developed into a major health crisis both in the United States as well as throughout the developed world. With current treatments limited to expensive, high-risk surgery and minimally efficacious pharmacotherapy, new therapeutic options are urgently needed to combat this alarming trend. This review focuses on the endogenous gut-brain signaling axes that regulate appetite under physiological conditions, and discusses their clinical relevance by summarizing the clinical and preclinical studies that have investigated manipulation of these pathways to treat obesity.

Amylin and the regulation of appetite and adiposity: recent advances in receptor signaling, neurobiology and pharmacology

PURPOSE OF REVIEW

This review focuses on recent advances in receptor signaling, neurobiology, and pharmacological interactions of amylin with nutritive status, as well as other metabolism-related regulatory signals.

RECENT FINDINGS

Manipulation of components of the amylin receptor complex revealed important roles for the accessory proteins of amylin receptors in energy balance. In-vitro findings point to potential novel sites of action and postreceptor signaling pathways activated by amylin. Neurobiological studies elucidated how amylin activation of hindbrain neural circuitry modulates hypothalamic signaling and responsiveness to leptin. The notion of 'amylin resistance' was addressed in several models (drug or diet-induced hyper-amylinemia). Finally, progress in the design and delivery of amylinomimetics is briefly discussed.

SUMMARY

Collectively, these mechanistic studies deepen our understanding of the role of endogenous amylin in the regulation of appetite and adiposity, and hopefully will help guide research efforts towards the development of more effective amylin-based therapies for metabolic diseases.