Highly specific and sensitive measurements of human and monkey interleukin 21 using sequential protein and tryptic peptide immunoaffinity LC-MS/MS.

A highly specific and sensitive immunoaffinity LC-MS/MS assay for quantification of human and cynomolgus monkey interleukin 21 (IL-21) was developed, qualified, and implemented. The workflow includes offline enrichment of IL-21 using an anti-IL-21 capture antibody, followed by isolation using magnetic beads, trypsin digestion, online enrichment of IL-21 derived tryptic peptides using antipeptide antibodies, and quantification using nanoflow LC-MS/MS. This assay was developed and qualified in human and cynomolgus monkey serum and tissues with a lower limit of quantitation of 0.78 pg/mL based on the intact cytokine. Both intra- and interbatch precision and accuracy, as well as stability and recovery, were found to be acceptable. IL-21 was not detected in serum from normal healthy volunteers or from autoimmune disease patients. However, IL-21 levels were quantified in cynomolgus monkey spleen and colon tissue and normal and inflammatory bowel disease (IBD) human colon tissue as well as hyperplasia human tonsils.

Selective amplification of glucocorticoid anti-inflammatory activity through synergistic multi-target action of a combination drug.

INTRODUCTION: Glucocorticoids are a mainstay of anti-inflammatory therapy, but significant adverse effects ultimately limit their utility. Previous efforts to design glucocorticoid structures with an increased therapeutic window have focused on dissociating anti-inflammatory transcriptional repression from adverse effects primarily driven by transcriptional activation. An alternative to this medicinal chemistry approach is a systems biology based strategy that seeks to amplify selectively the anti-inflammatory activity of very low dose glucocorticoid in immune cells without modulating alternative cellular networks that mediate glucocorticoid toxicity. METHODS: The combination of prednisolone and the antithrombotic drug dipyridamole was profiled using in vitro and in vivo models of anti-inflammatory activity and glucocorticoid-induced adverse effects to demonstrate a dissociated activity profile. RESULTS: The combination synergistically suppresses release of proinflammatory mediators, including tumour necrosis factor-alpha, IL-6, chemokine (C-C motif) ligand 5 (RANTES), matrix metalloproteinase-9, and others, from human peripheral blood mononuclear cells and mouse macrophages. In rat models of acute lipopolysaccharide-induced endotoxemia and delayed-type hypersensitivity, and in chronic models of collagen-induced and adjuvant-induced arthritis, the combination produced anti-inflammatory activity that required only a subtherapeutic dose of prednisolone. The immune-specific amplification of prednisolone anti-inflammatory activity by dipyridamole did not extend to glucocorticoid-mediated adverse effects, including corticosterone suppression or increased expression of tyrosine aminotransferase, in vivo after repeat dosing in rats. After 8 weeks of oral dosing in mice, treatment with the combination did not alter prednisolone-induced reduction in osteocalcin and mid-femur bone density, which are markers of steroid-induced osteoporosis. Additionally, amplification was not observed in the cellular network of corticotroph AtT-20/D16v-F2 cells in vitro, as measured by pro-opiomelanocortin expression and adrenocorticotropic hormone secretion. CONCLUSIONS: These data suggest that the multi-target mechanism of low-dose prednisolone and dipyridamole creates a dissociated activity profile with an increased therapeutic window through cellular network selective amplification of glucocorticoid-mediated anti-inflammatory signaling.

A model for studying Alzheimer's Abeta42-induced toxicity in Drosophila melanogaster.

Alzheimer's disease is a neurological disorder resulting in the degeneration and death of brain neurons controlling memory, cognition and behavior. Although overproduction of Abeta peptides is widely considered a causative event in the disease, the mechanisms by which Abeta peptides cause neurodegeneration and the processes of Abeta clearance and degradation remain unclear. To address these issues, we have expressed the Abeta peptides in Drosophila melanogaster. We show that overexpression of Abeta42 peptides in the nervous system results in phenotypes associated with neuronal degeneration in a dose- and age-dependent manner. We further show that a mutation in a Drosophila neprilysin gene suppresses the Abeta42 phenotypes by lowering the levels of the Abeta42 peptide, supporting the role of neprilysin in the catabolism of Abeta peptides in vivo. We propose that our Drosophila model is suitable for the study and elucidation of Abeta metabolism and toxicity at the genetic level.