During recent years combining GLP-1 and glucagon receptor agonism with the purpose of achieving superior weight loss and metabolic control compared to GLP-1 alone has received much attention. The superior efficacy has been shown by several in preclinical models but has been difficult to reproduce in humans. In this paper, we present the pre-clinical evaluation of NN1177, a long-acting GLP-1/glucagon receptor co-agonist previously tested in clinical trials. To further investigate the contribution from the respective receptors, two other co-agonists (NN1151, NN1359) with different GLP-1-to-glucagon receptor ratios were evaluated in parallel. In the process of characterizing NN1177, species differences and pitfalls in traditional pre-clinical evaluation methods were identified, highlighting the translational challenges in predicting the optimal receptor balance in humans. In diet-induced obese (DIO) mice, NN1177 induced a dose-dependent body weight loss, primarily due to loss of fat mass, and improvement in glucose tolerance. In DIO rats, NN1177 induced a comparable total body weight reduction, which was in contrast mainly caused by loss of lean mass, and glucose tolerance was impaired. Furthermore, despite long half-lives of the three co-agonists, glucose control during steady state was seen to depend on compound exposure at time of evaluation. When evaluated at higher compound exposure, glucose tolerance was similarly improved for all three co-agonists, independent of receptor balance. However, at lower compound exposure, glucose tolerance was gradually impaired with higher glucagon receptor preference. In addition, glucose tolerance was found to depend on study duration where the effect of glucagon on glucose control became more evident with time. To conclude, the pharmacodynamic effects at a given GLP-1-to-glucagon ratio differs between species, depends on compound exposure and study length, complicating the identification of an optimally balanced clinical candidate. The present findings could partly explain the low number of clinical successes for this dual agonism.
Helicobacter pylori is one of the most prevalent human pathogens in the world and is the aetiological agent of gastritis, peptic ulcer disease and gastric malignancies. In addition H. pylori and other novel members of the genus are capable of successfully colonising the bile-rich niche of the upper intestine and are associated with a diverse range of intestinal pathologies. Surface-enhanced laser desorption/ionisation-time of flight mass spectrometry was used to analyse surface extracts from H. pylori, Helicobacter bilis, Helicobacter pullorum and "Helicobacter sp. flexispira" to characterise cell surface changes following bile stress. The system detected two distinct response patterns to bile stress on the cell surface of Helicobacter spp. in vitro. The first involved the increase under bile stress of peaks at 7.6 and 7.9 kDa for H. billis and H. pullorum, respectively. In contrast both "Helicobacter sp. flexispira" and a clinical isolate of H. pylori had similar response profiles to bile stress. Both strains had at least three low mass peaks decreased under bile stress and a single peak induced by bile stress. The present study has established the use of ProteinChip(R) technology to analyse helicobacter-related proteomics. Specifically this study has established that different patterns are generated in response to bile stress among various pathogenic Helicobacter spp. which may give insights into the ability of these strains to colonise different niches.
The Helicobacter genus is associated with a wide spectrum of pathologies in the gastrointestinal tract. However, in contrast to Helicobacter pylori, few data are available regarding proteomic characteristics of enterohepatic helicobacters. Proteomic analysis of this genus has predominantly utilised two-dimensional gel electrophoresis methodology. In the present study we applied an innovative technique using ProteinChip arrays coupled with surface-enhanced laser desorption/ionisation time of flight mass spectroscopy to accurately assess the M(r) of proteins for comparative proteomic profiling. We analysed binding of outer membrane fractions to a weak cation exchange array for strains of H. pylori from culture collections and compared these profiles to fresh clinical isolates. In addition, we analysed profiles from Helicobacter pullorum, Helicobacter bilis and 'Helicobacter sp. flexispira'. The system proved rapid, accurate and reproducible. Distinct specific profiles for all the strains studied were identified. However, strains from culture collections that have undergone numerous subcultures had almost identical profiles. In contrast, profiles from fresh clinical isolates were markedly different. Moreover, certain features of the profiles from the enterohepatic species were conserved.
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