Corinna Schoelch

Normalization of Prandial Blood Glucose and Improvement of Glucose Tolerance by Liver-Specific Inhibition of SH2 Domain–Containing Inositol Phosphatase 2 (SHIP2) in Diabetic KKAy Mice: SHIP2 Inhibition Causes Insulin-Mimetic Effects on Glycogen Metabolism, Gluconeogenesis, and Glycolysis

Type 2 diabetes is characterized by a progressive resistance of peripheral tissues to insulin. Recent data have established the lipid phosphatase SH2 domain–containing inositol phosphatase 2 (SHIP2) as a critical negative regulator of insulin signal transduction. Mutations in the SHIP2 gene are associated with type 2 diabetes. Here, we used hyperglycemic and hyperinsulinemic KKAy mice to gain insight into the signaling events and metabolic changes triggered by SHIP2 inhibition in vivo. Liver-specific expression of a dominant-negative SHIP2 mutant in KKAy mice increased basal and insulin-stimulated Akt phosphorylation. Protein levels of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase were significantly reduced, and consequently the liver produced less glucose through gluconeogenesis. Furthermore, SHIP2 inhibition improved hepatic glycogen metabolism by modulating the phosphorylation states of glycogen phosphorylase and glycogen synthase, which ultimately increased hepatic glycogen content. Enhanced glucokinase and reduced pyruvate dehydrogenase kinase 4 expression, together with increased plasma triglycerides, indicate improved glycolysis. As a consequence of the insulin-mimetic effects on glycogen metabolism, gluconeogenesis, and glycolysis, the liver-specific inhibition of SHIP2 improved glucose tolerance and markedly reduced prandial blood glucose levels in KKAy mice. These results support the attractiveness of a specific inhibition of SHIP2 for the prevention and/or treatment of type 2 diabetes.

Acetyl-CoA carboxylases 1 and 2 show distinct expression patterns in rats and humans and alterations in obesity and diabetes.

Acetyl‐CoA carboxylases (ACC) 1 and 2 are central enzymes in lipid metabolism. To further investigate their relevance for the development of obesity and type 2 diabetes, expression of both ACC isoforms was analyzed in obese fa/fa Zucker fatty and Zucker diabetic fatty rats at different ages in comparison to Zucker lean controls.

Improved lipid profile through liver-specific knockdown of liver X receptor alpha in KKAy diabetic mice.

Nuclear hormone receptors liver X receptor (LXRalpha and LXRbeta) ligands are attractive approaches for the treatment of dyslipidemia and atherosclerosis. To further elucidate the function of LXRalpha in liver lipid metabolism in a disease-relevant animal model, the KKAy mouse, we used adenoviral vectors to selectively knock down LXRalpha gene expression. Out of five different short hairpin RNAs (shRNAs) that were tested in vitro, one construct was selected for detailed analysis of LXRalpha knockdown in vivo. Reduction of LXRalpha transcript levels to 48 +/- 13% compared with control virus transduction resulted in a significant downregulation of the LXRalpha-regulated lipogenic genes sterol-regulatory element binding protein-1c (SREBP1c) and stearoyl CoA desaturase 1 in vivo. Interestingly, ABCA1 and phoshoenolpyruvate carboxykinase 1 expression was not affected, whereas lipoprotein lipase (LPL) expression was found to be increased. In addition, 8 days after virus transduction, both plasma and liver triglycerides (TGs) were reduced by about 50%. Changes in TG levels were not due to reduced food intake in virus-treated animals, because pair-fed mice showed unchanged TG levels. Taken together, liver-specific knockdown of LXRalpha in vivo by shRNA reduced expression of lipogenic master genes, like SREBP1c, and improved the lipid profile of hypertriglyceridemic KKAy mice.

Safety, Pharmacokinetics, and Pharmacodynamics of Multiple Rising Doses of BI 655064, an Antagonistic Anti‐CD40 Antibody, in Healthy Subjects: A Potential Novel Treatment for Autoimmune Diseases

BI 655064 is a humanized antagonistic anti‐cluster of differentiation (CD) 40 monoclonal antibody that selectively blocks the CD40‐CD40L interaction. The CD40‐CD40L pathway is a promising treatment target for autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, and lupus nephritis. The safety, tolerability, pharmacokinetics, and pharmacodynamics of repeated once‐weekly BI 655064 subcutaneous dosing over 4 weeks were evaluated in a multiple‐dose study in healthy subjects. Subjects (N = 40) were randomized 4:1 to four sequential BI 655064 dose groups (80, 120, 180, 240 mg) or to placebo. Safety and tolerability, plasma exposure, CD40 receptor occupancy, and CD40L‐induced CD54 upregulation were assessed over 64 and 78 days for the 80‐ to 180‐mg and 240‐mg dose groups, respectively. BI 655064 exposure increased in a supraproportional manner, due to target‐mediated drug clearance, for doses between 80 mg and 120 mg, but was near proportional for doses greater than 120 mg. Terminal half‐life ranged between 6 and 8 days. Dose‐dependent accumulation of BI 655064 supports the use of a loading dose in future clinical studies. Following 4 weeks of dosing, >90% CD40 receptor occupancy and inhibition of CD54 upregulation were observed at all dose levels, lasting for 17 days after the last dose. BI 655064 was generally well tolerated. There were no serious adverse events and the frequency and intensity of adverse events were similar for BI 655064 and placebo; no dose relationship or relevant signs of an acute immune reaction were observed. These findings support further investigation of BI 655064 as a potential treatment for autoimmune diseases.

Influence of sub-chronic selective 11β-hydroxysteroid dehydrogenase 1 inhibition on the hypothalamic-pituitary-adrenal axis in female cynomolgus monkeys.

Inhibition of local cortisol regeneration from circulating cortisone by blocking 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) has been shown to ameliorate the risk factors associated with the metabolic syndrome. Chronic modulation of glucocorticoid homeostasis may result in hypothalamic-pituitary-adrenal (HPA) axis stimulation. HPA axis over-activation leading androgen excess would be undesirable in a therapeutic intervention designed to treat a chronic condition such as the metabolic syndrome. To address whether 11β-HSD1 inhibition would lead to excess androgens, we treated female cynomolgus monkeys with a selective inhibitor, BI 135558, for 4 weeks. Continual action of the compound over the dosing period was confirmed by constant plasma exposure, and a maintained change in urinary glucocorticoid metabolites consistent with 11β-HSD1 inhibition. No significant changes in adrenal function, as evidenced by an adrenocorticotropic hormone (ATCH) challenge, were observed. An examination of androgenic hormones revealed a slight increase in dehydroepiandrosterone sulfate (DHEA-S), while other hormones such as testosterone remained within reference values. Overall, treatment with BI 135558 in monkeys did not result in obvious over-activation of the HPA axis.