Tatiana Ort

A disease module in the interactome explains disease heterogeneity, drug response and captures novel pathways and genes in asthma

Recent advances in genetics have spurred rapid progress towards the systematic identification of genes involved in complex diseases. Still, the detailed understanding of the molecular and physiological mechanisms through which these genes affect disease phenotypes remains a major challenge. Here, we identify the asthma disease module, i.e. the local neighborhood of the interactome whose perturbation is associated with asthma, and validate it for functional and pathophysiological relevance, using both computational and experimental approaches. We find that the asthma disease module is enriched with modest GWAS P-values against the background of random variation, and with differentially expressed genes from normal and asthmatic fibroblast cells treated with an asthma-specific drug. The asthma module also contains immune response mechanisms that are shared with other immune-related disease modules. Further, using diverse omics (genomics, gene-expression, drug response) data, we identify the GAB1 signaling pathway as an important novel modulator in asthma. The wiring diagram of the uncovered asthma module suggests a relatively close link between GAB1 and glucocorticoids (GCs), which we experimentally validate, observing an increase in the level of GAB1 after GC treatment in BEAS-2B bronchial epithelial cells. The siRNA knockdown of GAB1 in the BEAS-2B cell line resulted in a decrease in the NFkB level, suggesting a novel regulatory path of the pro-inflammatory factor NFkB by GAB1 in asthma.

GLP-1 receptor activation inhibits VLDL production and reverses hepatic steatosis by decreasing hepatic lipogenesis in high-fat-fed APOE*3-Leiden mice.

Objective In addition to improve glucose intolerance, recent studies suggest that glucagon-like peptide-1 (GLP-1) receptor agonism also decreases triglyceride (TG) levels. The aim of this study was to evaluate the effect of GLP-1 receptor agonism on very-low-density lipoprotein (VLDL)-TG production and liver TG metabolism. Experimental Approach The GLP-1 peptide analogues CNTO3649 and exendin-4 were continuously administered subcutaneously to high fat diet-fed APOE*3-Leiden transgenic mice. After 4 weeks, hepatic VLDL production, lipid content, and expression profiles of selected genes involved in lipid metabolism were determined. Results CNTO3649 and exendin-4 reduced fasting plasma glucose (up to −30% and −28% respectively) and insulin (−43% and −65% respectively). In addition, these agents reduced VLDL-TG production (−36% and −54% respectively) and VLDL-apoB production (−36% and −43% respectively), indicating reduced production of VLDL particles rather than reduced lipidation of apoB. Moreover, they markedly decreased hepatic content of TG (−39% and −55% respectively), cholesterol (−30% and −55% respectively), and phospholipids (−23% and −36% respectively), accompanied by down-regulation of expression of genes involved in hepatic lipogenesis (Srebp-1c, Fasn, Dgat1) and apoB synthesis (Apob). Conclusion GLP-1 receptor agonism reduces VLDL production and hepatic steatosis in addition to an improvement of glycemic control. These data suggest that GLP-receptor agonists could reduce hepatic steatosis and ameliorate dyslipidemia in patients with type 2 diabetes mellitus.

Protein Engineering Strategies for Sustained Glucagon-Like Peptide-1 Receptor–Dependent Control of Glucose Homeostasis

OBJECTIVE—We have developed a novel platform for display and delivery of bioactive peptides that links the biological properties of the peptide to the pharmacokinetic properties of an antibody. Peptides engineered in the MIMETIBODY platform have improved biochemical and biophysical properties that are quite distinct from those of Fc-fusion proteins. CNTO736 is a glucagon-like peptide 1 (GLP-1) receptor agonist engineered in our MIMETIBODY platform. It retains many activities of native GLP-1 yet has a significantly enhanced pharmacokinetic profile. Our goal was to develop a long-acting GLP-1 receptor agonist with sustained efficacy. RESEARCH DESIGN AND METHODS—In vitro and in vivo activity of CNTO736 was evaluated using a variety of rodent cell lines and diabetic animal models. RESULTS—Acute pharmacodynamic studies in diabetic rodents demonstrate that CNTO736 reduces fasting and postprandial glucose, decreases gastric emptying, and inhibits food intake in a GLP-1 receptor–specific manner. Reduction of food intake following CNTO736 dosing is coincident with detection of the molecule in the circumventricular organs of the brain and activation of c-fos in regions protected by the blood-brain barrier. Diabetic rodents dosed chronically with CNTO736 have lower fasting and postprandial glucose and reduced body weight. CONCLUSIONS—Taken together, our data demonstrate that CNTO736 produces a spectrum of GLP-1 receptor–dependent actions while exhibiting significantly improved pharmacokinetics relative to the native GLP-1 peptide.

CNTO736, a Novel Glucagon-Like Peptide-1 Receptor Agonist, Ameliorates Insulin Resistance and Inhibits Very Low-Density Lipoprotein Production in High-Fat-Fed Mice

CNTO736 is a glucagon-like peptide (GLP) 1 receptor agonist that incorporates a GLP-1 peptide analog linked to the Mimetibody platform. We evaluate the potential of acute and chronic CNTO736 treatment on insulin sensitivity and very low-density lipoprotein (VLDL) metabolism. For acute studies, diet-induced insulin-resistant C57BL/6 mice received a single intraperitoneal injection of CNTO736 or vehicle. Chronic effects were studied after 4 weeks of daily intraperitoneal administration. A hyperinsulinemic-euglycemic clamp monitored insulin sensitivity. A single dose of CNTO736 reduced fasting plasma glucose levels (CNTO736, 4.4 ± 1.0; control, 6.3 ± 2.4 mM) and endogenous glucose production (EGP) (CNTO736, 39 ± 11; control, 53 ± 13 μmol/min/kg) and increased insulin-mediated glucose uptake (CNTO736, 76 ± 25; control, 54 ± 13 μmol/min/kg). Chronic administration of CNTO736 reduced fasting glucose levels (CNTO736, 4.1 ± 0.8; control 6.0 ± 1.0 mM), improved insulin-dependent glucose uptake (CNTO736, 84 ± 19; control, 61 ± 15 μmol/min/kg), and enhanced inhibition of EGP (CNTO736, 91 ± 18; control, 80 ± 10% inhibition). In addition, chronic dosing with CNTO736 reduced fasting EGP (CNTO736, 39 ± 9; control, 50 ± 8 μmol/min/kg) and VLDL production (CNTO736, 157 ± 23; control, 216 ± 36 μmol/h/kg). These results indicate that CNTO736 reinforces insulins action on glucose disposal and production in diet-induced insulin-resistant mice. In addition, CNTO736 reduces basal hepatic glucose and VLDL output in these animals. The data suggest that CNTO736 may be a useful tool in the treatment of type 2 diabetes.

A Novel EPO Receptor Agonist Improves Glucose Tolerance via Glucose Uptake in Skeletal Muscle in a Mouse Model of Diabetes

Patients treated with recombinant human Epo demonstrate an improvement in insulin sensitivity. We aimed to investigate whether CNTO 530, a novel Epo receptor agonist, could affect glucose tolerance and insulin sensitivity. A single administration of CNTO 530 significantly and dose-dependently reduced the area under the curve in a glucose tolerance test in diet-induced obese and diabetic mice after 14, 21, and 28 days. HOMA analysis suggested an improvement in insulin sensitivity, and this effect was confirmed by a hyperinsulinemic-euglycemic clamp. Uptake of 14C-2-deoxy-D-glucose indicated that animals dosed with CNTO 530 transported more glucose into skeletal muscle and heart relative to control animals. In conclusion, CNTO530 has a profound effect on glucose tolerance in insulin-resistant rodents likely because of improving peripheral insulin sensitivity. This effect was observed with epoetin-α and darbepoetin-α, suggesting this is a class effect, but the effect with these compounds relative to CNTO530 was decreased in duration and magnitude.

Epitope-dependent mechanisms of CD27 neutralization revealed by X-ray crystallography

&NA; CD27 is a T and B cell co‐stimulatory protein of the TNF receptor superfamily dependent on the availability of the TNF‐like ligand CD70. Two anti‐CD27 neutralizing monoclonal antibodies were obtained from mouse hybridoma and subsequently humanized and optimized for binding the target. The two antibodies are similar in terms of their CD27‐binding affinity and ability to block NF‐&kgr;B signaling, however their clearance rates in monkeys are very different. The pharmacokinetics profiles could be epitope dependent. To identify the epitopes, we determined the crystal structure of the ternary complex between CD27 and the Fab fragments of these non‐competing antibodies. The structure reveals the binding modes of the antibodies suggesting that their mechanisms of action are distinctly different and provides a possible explanation of the in vivo data. Graphical abstract Figure. No caption available. HighlightsTwo anti‐CD27 antibodies exhibit distinctly different pharmacokinetics in monkeys.Crystal structure of CD27 with both mAbs reveals their non‐overlapping epitopes.The different neutralization mechanisms of the two mAbs are linked to the epitopes.