Faculty Bibliography

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: 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

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

Background: The risk of developing Alzheimer's disease (AD) is magnified in individuals with metabolic dysfunction, specifically obesity and type 2 diabetes. In cases of insulin deficiency or resistance, elevated and fluctuating levels of blood glucose lead to the production of Advanced Glycation End Products (AGEs) that bind their receptor, RAGE, with pathological consequences. AGE-RAGE ligand binding induces intracellular signaling cascades, in part via the formin signal transduction effector, diaphanous- 1 (mDia1). Activation of this cellular mechanism activates NF-KB activation, upregulates pro-inflammatory molecules, increases RAGE expression, and ignites a positive feedback loop driving chronic inflammation in the periphery. Given that AGEs are increased in the brains of both diabetic and AD patients, here we investigate AGE-RAGE binding and subsequent mDia1 signal transduction as a possible mechanism of neuroinflammation, which contributes to the pathogenesis of AD. Methods: mDia1 and RAGE expression in microglia was evaluated by Immunoflourescent IHC in temporal cortex brain slices of AD and Non-Demented Aged human tissue. CD11b+ microglia were isolated from young (<10 month) and old (>16 month) APP London mice and aged matched controls and subjected to molecular analysis. BV-2 microglial- like cells were stimulated by the prototypic RAGE ligand, Carboxy Methyl Lysine (CML-AGE) (100 mug/mL) for 24 h, harvested, and Ager (RAGE), Drf1 (mDia1), Cd36, and Cd68RNA transcript levels were analyzed by q-RT-PCR. Results: mDia1 and RAGE are highly expressed in human AD and aged brain and colocalize, at least in part, to CD68+ activated microglia. mDia1 is highly expressed in CD11b+ microglia from APP London mice vs. aged matched controls. CML-AGE stimulated BV-2 cells display a 2-fold increased expression of mDia1, RAGE, CD36, and CD68 vs. vehicle treatment. Conclusions: RAGE and mDia1 are highly expressed in AD human brain, supporting their possible role in mediating pathogenesis. Acute stimulation with RAGE ligands upregulates inflammatory and phagocytosis markers in cultured BV-2 cells. Primary isolates of murine CD11b+ microglia demonstrate high levels of expression of mDia. These data suggest that RAGE may exert its pathogenic effects in AD brain, at least in part via mDia1-mediated neuroinflammation, thereby driving the AD phenotype. (Figure presented)

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder of largely unknown pathogenesis. Recent studies suggest that enhanced oxidative stress and neuroinflammation contribute to the progression of the disease. Mounting evidence implicates the receptor for advanced glycation end-products (RAGE) as a significant contributor to the pathogenesis of certain neurodegenerative diseases and chronic conditions. It is hypothesized that detrimental actions of RAGE are triggered upon binding to its ligands, such as AGEs (advanced glycation end products), S100/calgranulin family members, and High Mobility Group Box-1 (HMGB1) proteins. Here, we examined the expression of RAGE and its ligands in human ALS spinal cord. Tissue samples from age-matched human control and ALS spinal cords were tested for the expression of RAGE, carboxymethyllysine (CML) AGE, S100B, and HMGB1, and intensity of the immunofluorescent and immunoblotting signals was assessed. We found that the expression of both RAGE and its ligands was significantly increased in the spinal cords of ALS patients versus age-matched control subjects. Our study is the first report describing co-expression of both RAGE and its ligands in human ALS spinal cords. These findings suggest that further probing of RAGE as a mechanism of neurodegeneration in human ALS is rational.