The Role of Human IAPP in Stress and Inflammatory Processes in Type 2 Diabetes

Understanding the mechanisms regulating whole-body glucose homeostasis is important in order to understand what happens in a disease such as type 2 diabetes (T2D). Insulin resistance, inflammation, dysfunction of islet β-cells, and the presence of amyloid deposits in the pancreas are some of the major causes involved in the process of β-cell deterioration. The unique peptide constituent of amyloid deposits, human islet amyloid polypeptide (hIAPP), is capable of inducing endoplasmic reticulum (ER) stress and the resulting unfolded-protein response activation. Additionally, hIAPP has been shown to induce interleukin-1β expression, the main cytokine involved in inflammation and T2D causing inflammation and eventually, inducing apoptosis. Nevertheless, the mechanisms behind the process of hIAPP aggregation and amyloid formation are still unknown. In this chapter, we describe the different mechanisms by which hIAPP induces ER stress and inflammation. This should open the door for designing therapeutic interventions aimed at modulating the immune system and the ER stress response

Remission of obesity and insulin resistance is not sufficient to restore mitochondrial homeostasis in visceral adipose tissue

Metabolic plasticity is the ability of a biological system to adapt its metabolic phenotype to different environmental stressors. We used a whole-body and tissue-specific phenotypic, functional, proteomic, metabolomic and transcriptomic approach to systematically assess metabolic plasticity in diet-induced obese mice after a combined nutritional and exercise intervention. Although most obesity and overnutrition-related pathological features were successfully reverted, we observed a high degree of metabolic dysfunction in visceral white adipose tissue, characterized by abnormal mitochondrial morphology and functionality. Despite two sequential therapeutic interventions and an apparent global healthy phenotype, obesity triggered a cascade of events in visceral adipose tissue progressing from mitochondrial metabolic and proteostatic alterations to widespread cellular stress, which compromises its biosynthetic and recycling capacity. In humans, weight loss after bariatric surgery showed a transcriptional signature in visceral adipose tissue similar to our mouse model of obesity reversion. Overall, our data indicate that obesity prompts a lasting metabolic fingerprint that leads to a progressive breakdown of metabolic plasticity in visceral adipose tissue

Adherence to eHealth-Delivered Exercise in Adults with no Specific Health Conditions: A Scoping Review on a Conceptual Challenge

Adherence has emerged as a focal point and critical determinant of success for physical activity interventions. The term is used for both traditional and digital interventions, and for prescribed and nonprescribed activities. Many other terms for adherence are being used interchangeably, as there is no consensus on its precise conceptualization. This scoping review aimed to advance the definition of adherence to eHealth programs, specifically for the adult population with no specific health conditions. A total of 2983 papers, published between 1 January 2016 and 13 March 2022, were retrieved from different databases (including grey literature). Of those, 13 studies met the eligibility criteria and were included for review. The selected studies used a wide array of technologies and consisted mainly of exercise interventions. Most of the reviewed publications contemplated exercise adherence as a percentage of expected dose. Most (8 out of 13) studies neither assessed nor specified an expected use of the involved technology. Results suggest a need for homogeneity in the conceptualization of adherence to physical activity and exercise, including those interventions delivered digitally

Predicting Physical Exercise Adherence in Fitness Apps Using a Deep Learning Approach

The use of mobile fitness apps has been on the rise for the last decade and especially during the worldwide SARS-CoV-2 pandemic, which led to the closure of gyms and to reduced outdoor mobility. Fitness apps constitute a promising means for promoting more active lifestyles, although their attrition rates are remarkable and adherence to their training plans remains a challenge for developers. The aim of this project was to design an automatic classification of users into adherent and non-adherent, based on their training behavior in the first three months of app usage, for which purpose we proposed an ensemble of regression models to predict their behaviour (adherence) in the fourth month. The study was conducted using data from a total of 246 Mammoth Hunters Fitness app users. Firstly, pre-processing and clustering steps were taken in order to prepare the data and to categorize users into similar groups, taking into account the first 90 days of workout sessions. Then, an ensemble approach for regression models was used to predict user training behaviour during the fourth month, which were trained with users belonging to the same cluster. This was used to reach a conclusion regarding their adherence status, via an approach that combined affinity propagation (AP) clustering algorithm, followed by the long short-term memory (LSTM), rendering the best results (87% accuracy and 85% F1_score). This study illustrates the suggested the capacity of the system to anticipate future adherence or non-adherence, potentially opening the door to fitness app creators to pursue advanced measures aimed at reducing app attrition

Endogenous and chemical chaperones decrease ER stress markers in hIAPP-INS1E cells.

<p>A) BiP and tubulin levels were determined in hIAPP-INS1E cells previously transduced with Ad-BiP or Ad-GFP for 24 hours. Representative western blotting results showing protein expression levels of CHOP, ATF3, BiP, p-eIF2α and β-actin levels in hIAPP-INS1E cells cultured with B) 0.5 µM Thp for 8 hours or C) with 25 mM of glucose and 400 µM palmitic acid (HG+PA) for 24 hours. Representative results from 3 to 5 individual experiments are shown.</p

Thapsigargin and high glucose and palmitic acid potentiate ER stress gene expression in hIAPP-INS1E cells.

<p>ER stress expression markers CHOP, ATF3 and sXBP1 were determined by real-time PCR from hIAPP-INS1E, rIAPP-INS1E and INS1E control cells cultured at A) 11 mM glucose B) 11 mM glucose exposed to 0.5 µM of thapsigargin for 8 hours or C) 25 mM of glucose (HG) with 400 µM palmitic acid (PA) for 24 hours. Results are normalized to untreated INS1E, rIAPP-INS1E or hIAPP-INS1E cells (dashed line) and expressed as mean ± S.E.M from five independent experiments. *<i>p</i><0.05 **<i>p</i><0.01 and ***<i>p</i><0.001 <i>vs</i>. rIAPP and <i>^##p</i><0.01, <i>^###p</i><0.001 <i>vs</i>. INS1E control. n.s., not significant.</p

Increased BiP and PDI expression after adenoviral transduction does not affect cell viability.

<p>A) hIAPP-INS1E cells were transduced with different doses (MOI) for 24 hours. Representative Western blotting shows BiP protein levels at indicated doses. B) GFP expression after adenoviral (Ad-PDI/GFP) transduction in hIAPP-INS1E cells for 24 hours. Note an increase in GFP expression that correlates with an increase in MOI. C) Live/death viability assay showing no cell death in hIAPP-INS1E cells transduced for 24 hours with Ad-BiP. Western blotting and images in B and C are representative from 3 independent experiments.</p

Chaperone treatment prevents beta-cell dysfunction under high glucose and palmitic acid treatment.

<p>hIAPP-INS1E cells were transduced with Ad-BiP, Ad-PDI or treated with TUDCA or PBA for 24 hours. After 24 hours, cells were treated with 25 mM of glucose and palmitic acid (HG+PA). Glucose-stimulated insulin secretion was performed at low (2.8 mM) and high (16 mM) glucose using INS1E cells as control as expressed by % of insulin content. Insulin levels were determined by ELISA. Results are expressed as mean ± S.E.M from three independent experiments. ^##<i>p</i><0.05 <i>vs</i> INS1E control, *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001 <i>vs</i>. hIAPP-INS1E cells treated with HG+PA. No statistical differences were found between Con and BiP, PDI, TUDCA and PBA.</p

List of primer sequences used in qRT-PCR experiments.

<p>List of primer sequences used in qRT-PCR experiments.</p

Knockdown of CHOP protects hIAPP-INS1E cells from induced apoptosis.

<p>hIAPP-INS1E cells were transfected with 20 µM of siRNA CHOP or siRNA scramble (siRNA scr) as a control. Twenty-four hours after transfection, cells were treated with A) 0.5 µM Thp for 8 hours or B) high glucose (25 mM) and BSA-coupled palmitic acid (400 µM; HG+PA) for 24 hours, and protein expression levels for CHOP, ATF3 and tubulin were determined. Representative Western blotting images are represented from 3 to 5 individual experiments. Immunostaining (left panel) and quantification (right panel) of insulin positive beta-cells (red), cleaved caspase 3 (green) and nuclei (blue) of hIAPP-INS1E cells (Con) and hIAPP-INS1E cells transfected with siRNA scr or siRNA CHOP previously treated with C) Thp or D) HG+PA. Note the absence of cells containing insulin and cleaved caspsase 3 staining in cells transfected with siRNA CHOP as compared to Thp or HG+PA treated controls. Scale bar is 50 µm. Quantification is normalized to number of insulin + cells and expressed as mean ± S.E.M from three independent experiments. **<i>p</i><0.01 and ***<i>p</i><0.001 <i>vs</i>. controls. No statistical differences were found between controls and Thp siCHOP or HG+PA siCHOP.</p