Growth differentiation factor 15 neutralization does not impact anorexia or survival in lipopolysaccharide-induced inflammation.

Growth differentiation factor 15 (GDF15) causes anorexia and weight loss in animal models, and higher circulating levels are associated with cachexia and reduced survival in cancer and other chronic diseases such as sepsis. To investigate the role of sepsis-induced GDF15, we examined whether GDF15 neutralization via a validated and highly potent monoclonal antibody, mAB2, modulates lipopolysaccharide (LPS)-induced anorexia, weight loss, and mortality in rodents. LPS injection transiently increased circulating GDF15 in wild-type mice, decreased food intake and body weight, and increased illness behavior and mortality at a high dose. GDF15 neutralization with mAB2 did not prevent or exacerbate any of the effects of LPS. Similarly, in GDF15 knockout mice, the LPS effect on appetite and survival was comparable with that observed in wild-type controls. Therefore, effective inhibition of circulating active GDF15 via an antibody or via gene knockout demonstrated that survival in the LPS acute inflammation model was independent of GDF15.

Adipocyte OGT governs diet-induced hyperphagia and obesity.

Palatable foods (fat and sweet) induce hyperphagia, and facilitate the development of obesity. Whether and how overnutrition increases appetite through the adipose-to-brain axis is unclear. O-linked beta-D-N-acetylglucosamine (O-GlcNAc) transferase (OGT) couples nutrient cues to O-GlcNAcylation of intracellular proteins at serine/threonine residues. Chronic dysregulation of O-GlcNAc signaling contributes to metabolic diseases. Here we show that adipocyte OGT is essential for high fat diet-induced hyperphagia, but is dispensable for baseline food intake. Adipocyte OGT stimulates hyperphagia by transcriptional activation of de novo lipid desaturation and accumulation of N-arachidonyl ethanolamine (AEA), an endogenous appetite-inducing cannabinoid (CB). Pharmacological manipulation of peripheral CB1 signaling regulates hyperphagia in an adipocyte OGT-dependent manner. These findings define adipocyte OGT as a fat sensor that regulates peripheral lipid signals, and uncover an unexpected adipose-to-brain axis to induce hyperphagia and obesity.

A novel approach for quantitation of glucosylceramide in human dried blood spot using LC-MS/MS.

BACKGROUND: Glucosylceramide, an efficacy biomarker for Gaucher Type 1 disease, exhibits poor solubility in polar solvents and whole blood which makes it difficult to prepare a homogenous blood standard. RESULTS: We developed a novel method using standard addition approach by spiking a small volume of analyte solution on the surface of prespotted dried blood spot. The whole spots were punched out for subsequent extraction and LC-MS/MS analysis. The assay performance met all validation acceptance criteria. Glucosylceramide concentrations in 50 paired plasma and dry blood spot samples obtained from Gaucher Type 1 patients were tested and the results demonstrated the feasibility of using the DBS method for clinical biomarker monitoring. CONCLUSION: The new approach greatly improves assay precision and accuracy.