Faculty Bibliography

The hormone islet amyloid polypeptide (IAPP, or amylin) plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to beta-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced beta-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of beta-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.

Introduction: Although obstructive sleep apnea (OSA) is known to occur more frequently among patients with metabolic syndrome (MS), the functional relationship between OSA and MS remains unclear. Therefore, we aimed to traverse the genetic-association between OSA and MS using A systems biology approach. Methods: Candidate genes for OSA and MS were extracted from Comparative Toxicogenomics Database (https://urldefense.proofpoint.com/v2/url?u=http- 3A__ctdbase.org_help_goDisease&d=CwIBAg&c=j5oPpO0eBH1iio48DtsedbOBGmuw5jHLjgvtN2r4ehE&r =KRXeNoRy5_8lkSwAJG5vjS1yT0aFSItfe494dmkdSVs&m=m3yKLpCYD6gzdb_fMnv9VyavoXGgk7duRWkr5 hBqb7Q&s=H-qi2fTXsbHCwk-LkFNxgIHjRhCo1YrIWyRu87IlMYs&e= ). Overlapping genes associated with OSA and MS were then assembled by Functional Enrichment analysis tool (FunRich), and their biological functions were identified using the Gene Ontology (GO) approach with the Protein ANalysis THrough Evolutionary Relationships (PANTHER) tool. GO uses structured controlled vocabularies (ontologies) to describe key characteristics of a gene product, including: (1) molecular function/activity, (2) biological processes it is involved in, and (3) cellular components where it is located. Results: Of the genes associated OSA (6,586) and MS (15,228), 5,322 (81%) OSA genes) overlapped between the conditions. GO analyses revealed that these genes were often associated with metabolic diseases (25.3%), inflammation/oxidative stress (13.6%), neurotransmitter regulation (12.8%), behavior/cognitive function (8.9%), and neurodegenerative diseases (4.8%). The remaining 34.7% were associated with other biological functions (i.e., cellular processes, homeostasis and reproduction, etc.). Conclusion: The vast majority of OSA-related genes were also associated with MS, supporting the practice of screening for OSA among individuals with MS. Future lifestyle intervention programs for chronic care management should also focus on sleep as an interventional component to attain maximum benefits

The etiology of amyotrophic lateral sclerosis (ALS), a fatal motor neuron disorder characterized by progressive muscle weakness and spasticity, remains largely unknown. Approximately 5-10% of cases are familial, and of those, 15-20% are associated with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). Mutations of the SOD1 gene interrupt cellular homeostasis and contribute to cellular toxicity evoked by the presence of altered SOD1, along with other toxic species, such as advanced glycation end products (AGEs). AGEs trigger activation of their chief cell surface receptor, RAGE (receptor for advanced glycation end products), and induce RAGE-dependent cellular stress and inflammation in neurons, thereby affecting their function and leading to apoptosis. Here, we show for the first time that the expression of RAGE is higher in the SOD1 transgenic mouse model of ALS vs. wild-type mouse spinal cord. We tested whether pharmacological blockade of RAGE may delay the onset and progression of disease in this mouse model. Our findings reveal that treatment of SOD1 transgenic mice with soluble RAGE (sRAGE), a natural competitor of RAGE that sequesters RAGE ligands and blocks their interaction with cell surface RAGE, significantly delays the progression of ALS and prolongs life span compared to vehicle treatment. We demonstrate that in sRAGE-treated SOD1 transgenic animals at the final stage of the disease, a significantly higher number of neurons and lower number of astrocytes is detectable in the spinal cord. We conclude that RAGE antagonism may provide a novel therapeutic strategy for ALS intervention.

INTRODUCTION: This review focuses on the multi-ligand receptor of the immunoglobulin superfamily - receptor for advanced glycation endproducts (RAGE). The accumulation of the multiple ligands of RAGE in cellular stress milieux links RAGE to the pathobiology of chronic disease and natural aging. Areas covered: In this review, we present a discussion on the ligands of RAGE and the implications of these ligand families in disease. We review the recent literature on the role of ligand-RAGE interaction in the consequences of natural aging; the macro- and microvascular complications of diabetes; obesity and insulin resistance; autoimmune disorders and chronic inflammation; and tumors and Alzheimer's disease. We discuss the mechanisms of RAGE signaling through its intracellular binding effector molecule - the formin DIAPH1. Physicochemical evidence of how the RAGE cytoplasmic domain binds to the FH1 (formin homology 1) domain of DIAPH1, and the consequences thereof, are also reviewed. Expert opinion: We discuss the modalities of RAGE antagonism currently in preclinical and clinical studies. Finally, we present the rationale behind potentially targeting the RAGE cytoplasmic domain-DIAPH1 interaction as a logical strategy for therapeutic intervention in the pathological settings of chronic diseases and aging wherein RAGE ligands accumulate and signal.

Background: The receptor for advanced glycation products (RAGE) is a member of the immunoglobulin superfamily able to regulate chronic inflammation. The prolonged AGE exposition in kidney, liver, and lung induces up regulation of alphaSMA, the main marker of myofibroblasts activation, resulting in an accumulation of extracellular matrix components (ECM) and consequent fibrosis. At intestinal level fibrosis is a common and severe compliance of inflammatory bowel disease (IBD), and inflamed colonic mucosa of patients with active IBD shows a significant increase of AGE and RAGE. Our aim was to determine the role of RAGE in intestinal fibrosis. Methods: Fibrosis was induced in C57BL/6 wild-type (WT) and RAGE-/- mice by for 3 cycles of 2,5% (w/v) dextran sulfate sodium (DSS) administration for 6 weeks, macroscopic (including dilation, thickness, and adhesion) and microscopic lesions (inflammation by Hematoxylin/Eosin and collagen deposition by Picrosirius red staining) were scored for all colonic specimens. mRNA expression of the main profibrotic mediator, TGF-beta (Tgf-beta1 gene), alphaSMA (ACTA-1 gene), and the expression of ECM components, mainly collagen types I-III (Col1A1 gene) and fibronectin (FN-1 gene), was evaluated by quantitative RT-polymerase chain reaction (PCR). Moreover, RAGE gene expression levels were evaluated in TGF-beta-stimulated intestinal fibroblasts and epithelial cells, as well as in human primary intestinal fibroblasts isolated from IBD patients Results: Compared with WT mice, DSS-treated C57/Bl6 RAGE- /- mice showed a lower colon weight/length ratio (29%, p < 0.0001), an indicator of wall thickening. In RAGE-/-mice, the macroscopic score was significantly reduced compared with WT mice (6 +/- 0.92 vs 1.43 +/- 0.54, p < 0.0001). DSS-treated RAGE-/- mice showed less then 50% (p < 0.001) of total microscopic score valued in WT mice. DSS administration also induced significant increase of Tgf-beta1, ACTA-1, Col1A1, and FN-1 gene expression in WT mice colon. DSS-treated RAGE-/- mice showed lower expression of Col1A1 (3.17 fold, p < 0.01), Tgf-beta1 (2 fold, p < 0.01), ACTA-1 (1.2 fold, p < 0.05) than WT mice, whereas FN-1 expression was totally prevented. In addition, myofibroblasts deriving by TGF-beta-treated intestinal fibroblasts and epithelial cells showed enhanced mRNA RAGE expression by 1.5 fold (p < 0.01) and 2.3 fold (p < 0.01), respectively. Additionally, in primary human intestinal fibroblasts, obtained by UC patients, a significant increase by 3.8 fold (p < 0.05) of RAGE gene expression was observed. Conclusions: The potential profibrotic role of RAGE in the development of intestinal fibrosis could shed light into the complex and dynamic fibrogenic processes in IBD

Diabetes exacerbates cardiovascular disease, at least in part via suppression of macrophage cholesterol efflux and levels of the cholesterol transporters, ATP binding cassette transporters A1 (ABCA1) and ABCG1. The receptor for advanced glycation end products (RAGE) is highly expressed in human and murine diabetic atherosclerotic plaques, particularly in macrophages. We tested the hypothesis that RAGE suppresses macrophage cholesterol efflux and probed the mechanisms by which RAGE downregulates ABCA1 and ABCG1. Macrophage cholesterol efflux to Apolipoprotein A1 (ApoA1) and High Density Lipoprotein (HDL) and reverse cholesterol transport to plasma, liver and feces were reduced in diabetic macrophages via RAGE. In vitro, RAGE ligands suppressed ABCG1 and ABCA1 promoter luciferase activity and transcription of ABCG1 and ABCA1 through PPARG-responsive promoter elements, but not through Liver X Receptor (LXR) elements. Plasma levels of HDL were reduced in diabetic mice in a RAGE-dependent manner. Laser capture microdissected CD68+ macrophages from atherosclerotic plaques of Ldlr-/- mice devoid of Ager (RAGE) displayed higher levels of Abca1, Abcg1 and Pparg mRNA transcripts vs. Ager-expressing Ldlr-/- mice, in a manner independent of glycemia or plasma levels of total cholesterol and triglyceride. Antagonism of RAGE may fill an important therapeutic gap in the treatment of diabetic macrovascular complications.

We present a new approach to population health, in which data-driven predictive models are learned for outcomes such as type 2 diabetes. Our approach enables risk assessment from readily available electronic claims data on large populations, without additional screening cost. Proposed model uncovers early and late-stage risk factors. Using administrative claims, pharmacy records, healthcare utilization, and laboratory results of 4.1 million individuals between 2005 and 2009, an initial set of 42,000 variables were derived that together describe the full health status and history of every individual. Machine learning was then used to methodically enhance predictive variable set and fit models predicting onset of type 2 diabetes in 2009-2011, 2010-2012, and 2011-2013. We compared the enhanced model with a parsimonious model consisting of known diabetes risk factors in a real-world environment, where missing values are common and prevalent. Furthermore, we analyzed novel and known risk factors emerging from the model at different age groups at different stages before the onset. Parsimonious model using 21 classic diabetes risk factors resulted in area under ROC curve (AUC) of 0.75 for diabetes prediction within a 2-year window following the baseline. The enhanced model increased the AUC to 0.80, with about 900 variables selected as predictive (p < 0.0001 for differences between AUCs). Similar improvements were observed for models predicting diabetes onset 1-3 years and 2-4 years after baseline. The enhanced model improved positive predictive value by at least 50% and identified novel surrogate risk factors for type 2 diabetes, such as chronic liver disease (odds ratio [OR] 3.71), high alanine aminotransferase (OR 2.26), esophageal reflux (OR 1.85), and history of acute bronchitis (OR 1.45). Liver risk factors emerge later in the process of diabetes development compared with obesity-related factors such as hypertension and high hemoglobin A1c. In conclusion, population-level risk prediction for type 2 diabetes using readily available administrative data is feasible and has better prediction performance than classical diabetes risk prediction algorithms on very large populations with missing data. The new model enables intervention allocation at national scale quickly and accurately and recovers potentially novel risk factors at different stages before the disease onset.

Introduction: To provide longer-term follow-up of a previously published pilot randomized trial comparing bariatric surgery vs. intensive medical weight management (MWM) in patients with type 2 diabetes (T2DM) and BMI 30-35. Additionally, to assess whether the soluble form of RAGE (receptor for advanced glycation end-products) is an adequate diabetes biomarker that may help determine which patient population would benefit most from surgery. Methods: Originally, 57 patients with T2DM and BMI 30-35 were randomized to surgery (bypass, sleeve or band, based on patient preference; n=29) vs. MWM (n=28). The 6 month results showed that surgery was significantly effective (previously published data). We performed an updated review of this patient cohort to evaluate weight loss and diabetes remission at 2 years. A repeated measures linear model was created to compare the change in HbA1C and BMI between the two groups. The outcomes were also compared to baseline sRAGE status using a repeated measures linear model. Patients who ultimately crossed over from MWM to surgery group (after the initial study) were included. Results: At baseline, mean BMI was 32.6 and mean HbA1c was 7.8. At 2 years the following was noted: The surgery group continued to have significantly higher diabetes remission (50% vs. 0%), lower BMI (28.5 vs. 30.9; p<0.0001) and lower HbA1c (7.0 vs. 7.9; p=0.019) than the MWM group. In the surgical group, those with a higher baseline sRAGE had a lower post-op BMI (p=0.037). Conclusion: At 2 years, bariatric surgery was very effective in patients with T2DM and BMI 30-35. Higher baseline sRAGE predicted success with surgery. However, larger studies will be required to confirm the accuracy of these observations

Introduction: Inflammatory bowel diseases (IBD) are chronic and relapsing, lifelong diseases of the gastrointestinal tract. Environmental factors which have a crucial role in the development of these diseases remain largely unknown. Few studies have described Advanced Glycation End-Products (AGE) as potential contributors of intestinal inflammation, and the role of AGE and their receptor RAGE in the pathophysiology of IBD are not yet fully elucidated. Aims & Methods: The global aim of our study was to address the link between AGE, RAGE, and IBD which might help to better understand the role of nutrition, as a major source for AGE, in the pathophysiology of IBD. Three different models of intestinal and colonic inflammation (indomethacin, dextran sodium sulfate (DSS) and trinitro benzene sulfonic acid (TNBS)) were induced in C57BL/6 wild type (WT) and RAGE null mice. In a second set of experiments, mice were orally administered with the food derived ligand for RAGE, carboxymethyllysine-bovine serum albumin (CML-BSA) or control BSA for 30 days; then, intestinal and colonic inflammation were induced. Severity of inflammation was evaluated using macroscopic, histologic and molecular parameters in the small intestine and colon of mice. Results: Following indomethacin administration, a significant decrease in ulcerations number and area was observed in the duodenum, jejunum and ileum of RAGE null mice compared to WT mice. Consistently, IL1b mRNA levels were significantly decreased in the three intestinal segments. RAGE null mice were protected from DSS- and TNBS-induced colitis, with a significant decrease of clinical and macroscopic parameters. Myeloperoxidase (MPO) activity, reflecting the neutrophil infiltration, was also significantly reduced in the colon of TNBStreated RAGE null mice compared to TNBS- treated WT mice. IL1b and iNOS mRNA expression were significantly decreased in colitic RAGE null mice compared to colitic WT mice. Chronic BSA-CML administration to mice worsened indomethacin-induced enteritis, as evidenced by a significant increase in ulcerations number and area in the duodenum, jejunum and ileum compared to control BSA-treated mice. Consistently, MPO activity and oxidative stress assessed by anion superoxide dosage were significantly increased in the ileum of CML BSAtreated mice compared to control BSA-treated mice. Chronic CML-BSA administration did not induce any effect on colonic inflammation. Conclusion: We demonstrated that RAGE signaling pathway is implicated in intestinal and colonic inflammation in mice. We showed that BSA-CML might be a dietary factor involved in intestinal inflammation. The role of RAGE and AGE in IBD now merits further investigations