Faculty Bibliography

The role of high-density lipoprotein (HDL) function and advanced glycation end products (AGEs) in HIV-related atherosclerotic cardiovascular disease (CVD) is unclear. Both glycation and oxidation (HDLox) are major modifications of HDL that can alter its composition and function. Therefore, we explored the longitudinal association of HDLox with progression of glycation, as evaluated by measurement of circulating forms of receptor for AGE that predict morbidity (soluble Receptors for Advanced Glycation Endproducts [sRAGE], endogenous secretory Receptors for Advanced Glycation Endproducts [esRAGE]), in people with HIV-1 (PWH; HIV-1) and uninfected (HIV-1) individuals.We retrospectively assessed if levels of plasma sRAGE and esRAGE and HDL function (reduced antioxidant function is associated with increased HDL lipid hydroperoxide content; HDLox) in a subset of participants (n = 80) from a prospective 3-year study (AIDS Clinical Trials Group A5078). Primary outcomes were baseline and yearly rates of change over 96 of 144 weeks (Δ) in HDLox in HIV-1 versus uninfected HIV-1 controls (noted as HIV-1).Higher baseline levels of sRAGE in PWH on effective anti-retroviral therapy and with low CVD risk, but not in HIV-1 persons, were independently associated with higher HDLox. EsRAGE, but not sRAGE, had consistent inverse relationships with ΔHDLox in both HIV-1 and HIV-1 persons at baseline. In HIV-1 but not in HIV-1 persons, ΔHDLox had positive and inverse relationships with ΔRAGE and ΔesRAGE, respectively.Glycation and oxidation of HDL may contribute to impaired HDL function present in PWH.

Human islet amyloid polypeptide (hIAPP) is a hormone secreted from β-cells in the Islets of Langerhans in response to the same stimuli that lead to insulin secretion. hIAPP plays an adaptive role in glucose homeostasis, but misfolds to form insoluble, fibrillar aggregates in type-II diabetes that are associated with the disease. Along the misfolding pathway, hIAPP forms species that are toxic to β-cells, resulting in reduced β-cell mass. hIAPP contains a strictly conserved disulfide bond between residues 2-7, which forms a small loop at the N-terminus of the molecule. The loop is located outside of the cross β-core in all models of the hIAPP amyloid fibrils. Mutations in this region are rare, and the disulfide loop plays a role in receptor binding, but the contribution of this region to the aggregation of hIAPP is not well understood. We define the role of the disulfide by analyzing a collection of analogues that remove the disulfide, by mutation of Cys to Ser, by reduction and modification of the Cys residues, or by deletion of the first seven residues. The cytotoxic properties of hIAPP are retained in the Cys to Ser disulfide free mutant. Removal of the disulfide bond accelerates amyloid formation in all constructs, both in solution and in the presence of model membranes. Removal of the disulfide reduces the ability of hIAPP to induce leakage of vesicles made up of POPS and POPC. Smaller effects are observed with vesicle that contain 40 mole percent cholesterol, although N-terminal truncation still reduces leakage.

Our previous work has shown that the cytoplasmic tail (ct) of RAGE is essential for RAGE ligand-mediated signal transduction and consequent modulation of gene expression and cellular properties. RAGE signaling requires interaction of ctRAGE with the intracellular effector, mammalian diaphanous 1, or DIAPH1. Given the complex, multi-ligand nature of ligands binding to the extracellular domains of RAGE, we sought to discover small molecule inhibitors of the interaction of ctRAGE with DIAPH1. Prompted by our identification of 13 small molecules that block the interaction of ctRAGE-DIAPH1, we pursued structure-activity relationship experiments to identify analogues potentially able to delay or prevent the progression of RAGE-related chronic diseases, such as diabetes. In vitro binding studies Native tryptophan fluorescence experiments were conducted using 1mM of compound dissolved in phosphate buffer and DMSO. 10 nM ctRAGE solution was titrated from 0.1 nM-100 muM and the dissociation constants, Kd, were estimated from the changes in peak fluorescence intensities as a function of the free compound concentration. NMR experiments were performed operating at 1H frequencies of 500 MHz and 700 MHz. NMR samples contained 50 muM of [U-15N] ctRAGE and 10 muM of the compound. All spectra were collected at 298K, which yielded high quality NMR spectra of [U-15N] RAGE tail. Compound binding to ctRAGE was identified as at least a 0.01 ppm change in the ctRAGE chemical shift. Small molecule leads were identified and referred to as NYU 1-5 (Table 1). Ex vivo biological activity assays Inhibition of smooth muscle cell (SMC) migration induced by RAGE ligands after incubation with indicated NYU compounds. SMCs were grown to confluence and starved overnight. The next morning, the medium was removed, compounds were added and the monolayer was wounded using a p200 pipette tip and allowed to incubate for 1.5h. Following incubation, compounds were removed and fresh medium containing the RAGE ligand, CML-AGE (10 mug/ml) was added for 4h. Images were taken, measured and an area ingrowth of effective migrating cells was calculated (Table 1). In vivo studies (A) Delayed type hypersensitivity. Female CF-1 mice were sensitized over the left inguinal lymph node with a methylated bovine serum albumin emulsion. On day 19 and 20 after sensitization, mice received, by oral gavage, the test compounds (5 mg/kg/bw) or vehicle twice daily. Post-final compound injection, mBSA was injected into the left hind paw. Inflammation was assessed using a semiquantitative scoring system (Figure 1). (B) Myocardial infarction in diabetic mice. Male C57BL/6 mice were rendered diabetic with STZ and were diabetic for 2 months. Mice were subjected to left anterior descending coronary artery occlusion followed by reperfusion (LAD/reperfusion). After 48h, the hearts were excised. TTC and Evan's blue staining was used to measure infarct area. Mice received a total of 7 doses of either VEHICLE or an NYU compound (Figure 2). In summary, refined compounds that inhibit the interaction of ctRAGE with DIAPH1, which exhibit in vitro and in vivo inhibition of RAGE-dependent molecular processes, present attractive scaffolds for the development of therapeutics against RAGE-mediated diseases, such as those linked to diabetic complications and chronic inflammation. We conclude that these identified compounds hold significant potential as druggable scaffolds for further development and testing for the treatment of RAGE-related disorders

BACKGROUND:An influx of lipid-loaded macrophages characterizes visceral adipose tissue (VAT) inflammation, which is an important factor in the development of insulin resistance (IR) in obesity. Depletion of macrophage lipids accompanies increased whole body insulin sensitivity, but the underlying mechanism is unknown. Deficiency of autophagy protein ATG16L1 is associated with increases in inflammatory diseases and lipid metabolism, but the connection between ATG16L1, IR, and obesity remains elusive. We hypothesize that myeloid ATG16L1 contributes to lipid loading in macrophages and to IR. METHODS:Wild-type (WT) bone marrow derived macrophages (BMDMs) were treated with fatty acids and assessed for markers of autophagy. Myeloid-deficient Atg16l1 and littermate control male mice were fed high fat diet (HFD) or low fat diet (LFD) for 3 months starting at 8 weeks of age. Mice were assessed for body mass, fat and lean mass, glucose and insulin sensitivity, food consumption and adipose inflammation. Fluorescence-activated cell sorted VAT macrophages were assessed for lipid content and expression of autophagy related genes. RESULTS:VAT and VAT macrophages from HFD-fed WT mice did not show differences in autophagy protein and gene expression compared to tissue from LFD-fed mice. Fatty acid-treated BMDMs increased neutral lipid content but did not change autophagy protein expression. HFD-fed Atg16l1 myeloid-deficient and littermate mice demonstrated no differences in body mass, glucose or insulin sensitivity, food consumption, fat or lean mass, macrophage lipid content, or adipose tissue inflammation. CONCLUSION/CONCLUSIONS:ATG16L1 does not contribute to obesity, IR, adipose tissue inflammation or lipid loading in macrophages in mice fed HFD.

Islet amyloidosis is characterized by the aberrant accumulation of islet amyloid polypeptide (IAPP) in pancreatic islets, resulting in β cell toxicity, which exacerbates type 2 diabetes and islet transplant failure. It is not fully clear how IAPP induces cellular stress or how IAPP-induced toxicity can be prevented or treated. We recently defined the properties of toxic IAPP species. Here, we have identified a receptor-mediated mechanism of islet amyloidosis-induced proteotoxicity. In human diabetic pancreas and in cellular and mouse models of islet amyloidosis, increased expression of the receptor for advanced glycation endproducts (RAGE) correlated with human IAPP-induced (h-IAPP-induced) β cell and islet inflammation, toxicity, and apoptosis. RAGE selectively bound toxic intermediates, but not nontoxic forms of h-IAPP, including amyloid fibrils. The isolated extracellular ligand-binding domains of soluble RAGE (sRAGE) blocked both h-IAPP toxicity and amyloid formation. Inhibition of the interaction between h-IAPP and RAGE by sRAGE, RAGE-blocking antibodies, or genetic RAGE deletion protected pancreatic islets, β cells, and smooth muscle cells from h-IAPP-induced inflammation and metabolic dysfunction. sRAGE-treated h-IAPP Tg mice were protected from amyloid deposition, loss of β cell area, β cell inflammation, stress, apoptosis, and glucose intolerance. These findings establish RAGE as a mediator of IAPP-induced toxicity and suggest that targeting the IAPP/RAGE axis is a potential strategy to mitigate this source of β cell dysfunction in metabolic disease.

BACKGROUND:The United Arab Emirates (UAE) is faced with a rapidly increasing burden of non-communicable diseases including obesity, diabetes, and cardiovascular disease. The UAE Healthy Future study is a prospective cohort designed to identify associations between risk factors and these diseases amongst Emiratis. The study will enroll 20,000 UAE nationals aged ≥18 years. Environmental and genetic risk factors will be characterized and participants will be followed for future disease events. As this was the first time a prospective cohort study was being planned in the UAE, a pilot study was conducted in 2015 with the primary aim of establishing the feasibility of conducting the study. Other objectives were to evaluate the implementation of the main study protocols, and to build adequate capacity to conduct advanced clinical laboratory analyses. METHODS:Seven hundred sixty nine UAE nationals aged ≥18 years were invited to participate voluntarily in the pilot study. Participants signed an informed consent, completed a detailed questionnaire, provided random blood, urine, and mouthwash samples and were assessed for a series of clinical measures. All specimens were transported to the New York University Abu Dhabi laboratories where samples were processed and analyzed for routine chemistry and hematology. Plasma, serum, and a small whole blood sample for DNA extraction were aliquoted and stored at -80 °C for future analyses. RESULTS:Overall, 517 Emirati men and women agreed to participate (68% response rate). Of the total participants, 495 (95.0%), 430 (82.2%), and 492 (94.4%), completed the questionnaire, physical measurements, and provided biological samples, respectively. CONCLUSIONS:The pilot study demonstrated the feasibility of recruitment and completion of the study protocols for the first large-scale cohort study designed to identify emerging risk factors for the major non-communicable diseases in the region.

INTRODUCTION/BACKGROUND:Self-reported tobacco use in the United Arab Emirates is among the highest in the region. Use of tobacco products other than cigarettes is widespread, but little is known about specific behavior use patterns. There have been no studies that have biochemically verified smoking status. METHODS:The UAE Healthy Future Study (UAEHFS) seeks to understand the causes of non-communicable diseases through a 20,000-person cohort study. During the study pilot, 517 Emirati nationals were recruited to complete a questionnaire, provide clinical measurements and biological samples. Complete smoking data were available for 428 participants. Validation of smoking status via cotinine testing was conducted based on complete questionnaire data and matching urine samples for 399 participants, using a cut-off of 200ng/ml to indicate active smoking status. RESULTS:Self-reported tobacco use was 36% among men and 3% among women in the sample. However, biochemical verification of smoking status revealed that 42% men and 9% of women were positive for cotinine indicating possible recent tobacco use. Dual and poly-use of tobacco products was fairly common with 32% and 6% of the sample reporting respectively. CONCLUSIONS:This is the first study in the region to biochemically verify tobacco use self-report data. Tobacco use in this study population was found to be higher than previously thought, especially among women. Misclassification of smoking status was more common than expected. Poly-tobacco use was also very common. Additional studies are needed to understand tobacco use behaviors and the extent to which people may be exposed to passive tobacco smoke. IMPLICATIONS/CONCLUSIONS:This study is the first in the region to biochemically verify self-reported smoking status.