Anorectic Gut Hormones PYY and GLP-1 on Brain Appetite Pathways: A Human fMRI Study.

This thesis explores the roles of the gut hormones Peptide YY (PYY) and glucagon-like peptide 1 (GLP-1) in the modulation of human brain reward pathways utilising functional magnetic resonance imaging (fMRI). PYY and GLP-1 are co-released post-prandially and both have been shown to reduce appetite and inhibit food intake when administered to humans. They have the potential to be developed into anti-obesity therapies, with the expectation that low-dose combination therapy may provide more effective weight loss and limited side effects. There are currently no safe and effective medications available to treat obesity, and yet this global health crisis continues unabated. In this context, a study of the mechanisms by which gut hormones exert their anorectic effects, may guide the rational development of new drugs. To date, the effects of GLP-1 alone and the ways in which PYY and GLP-1 combine to modulate brain activity in humans are unknown. This thesis contains a set of functional MRI experiments designed to determine these effects in healthy, fasted, normal-weight human subjects. Results are compared with the changes in brain activation patterns observed physiologically following a meal. For the first time in humans, I have demonstrated that, in conjunction with a comparable effect on lunchtime energy intake, combined infusion of PYY3-36 and GLP-17-36amide to fasted subjects results in a similar modulation of brain activity as observed following a large breakfast. This supports the proposal that these hormones are major physiological mediators of satiety in humans. Both the fed state and the administration of anorectic gut hormones to fasted subjects, reduces activation in multiple brain reward regions in response to visual food-cues. This confirms that circulating gut hormones modulate the hedonic processing of food. The lack of any obvious differential activation pattern between PYY3-36 and GLP-17- 36amide raises the possibility that they act at corticolimbic structures via a final common pathway

Rimonabant: From RIO to Ban

Endocannabinoid antagonism as a treatment for obesity and the metabolic syndrome became a hugely anticipated area of pharmacology at the start of the century. The CB1 receptor antagonist Rimonabant entered the European mass market on the back of several trials showing weight loss benefits alongside improvements in numerous other elements of the metabolic syndrome. However, the drug was quickly withdrawn due to the emergence of significant side effects—notably severe mood disorders. This paper provides a brief overview of the Rimonabant story and places the recent spate of FDA rejections of other centrally acting weight loss drugs entering Phase 3 trials in this context

Anti-nociceptive and desensitizing effects of olvanil on capsaicin-induced thermal hyperalgesia in the rat

Background: Olvanil (NE 19550) is a non-pungent synthetic analogue of capsaicin, the natural pungent ingredient of capsicum which activates the transient receptor potential vanilloid type-1 (TRPV1) channel and was developed as a potential analgesic compound. Olvanil has potent anti-hyperalgesic effects in several experimental models of chronic pain. Here we report the inhibitory effects of olvanil on nociceptive processing using cultured dorsal root ganglion (DRG) neurons and compare the effects of capsaicin and olvanil on thermal nociceptive processing in vivo; potential contributions of the cannabinoid CB1 receptor to olvanil’s anti-hyperalgesic effects were also investigated.Methods: A hot plate analgesia meter was used to evaluate the anti-nociceptive effects of olvanil on capsaicin-induced thermal hyperalgesia and the role played by CB1 receptors in mediating these effects. Single cell calcium imaging studies of DRG neurons were employed to determine the desensitizing effects of olvanil on capsaicin-evoked calcium responses. Statistical analysis used Student’s t test or one way ANOVA followed by Dunnett’s post-hoctest as appropriate.Results: Both olvanil (100 nM) and capsaicin (100 nM) produced significant increases in intracellular calcium concentrations [Ca2+]I in cultured DRG neurons. Olvanil was able to des ensitise TRPV1 responses to further capsaicin exposure more effectively than capsaicin. Intra plantar injection of capsaicin (0.1, 0.3 and 1μg) produced a robust TRPV1-dependant thermal hyperalgesia in rats, whilst olvanil (0.1, 0.3 and 1μg) produced no hyperalgesia, emphasizing its lack of pungency. The highest dose of olvanil significantly reduced the hyperalgesic effects of capsaicin in vivo. Intraplantar injection of the selective cannabinoid CB1 receptor antagonist rimonabant (1μg) altered neither capsaicin-induced thermal hyperalgesia nor the desensitizing properties of olvanil, indicating a lack of involvement of CB1receptors.Conclusions: Olvanil is effective in reducing capsaicin-induced thermal hyperalgesia, probably via directly desensitizingTRPV1 channels in a CB 1 receptor-independent fashion. The results presented clearly support the potential for olvanil in the development of new topical analgesic preparations for treating chronic pain conditions while avoiding the unwanted side effects of capsaicin treatments

Thermal imaging is a non-invasive alternative to PET-CT for measurement of brown adipose tissue activity in humans

Background Obesity and its metabolic consequences are a major cause of morbidity and mortality. Brown adipose tissue (BAT) utilises glucose and free fatty acids to produce heat, thereby increasing energy expenditure. Effective evaluation of human BAT stimulators is constrained by current standard BAT assessment methods as positron emission tomography-computed tomography (PET-CT) requires exposure to high doses of ionising radiation. Infrared thermography (IRT) is a potential non-invasive, safe alternative, although direct corroboration with PET-CT has not previously been established. Methods IRT and 18F-fluorodeoxyglucose (¹⁸F-FDG) PET-CT data from 8 healthy male participants subjected to water jacket cooling were directly compared. Thermal images (TIs) were geometrically transformed to overlay PET-CT-derived maximum intensity projection (MIP) images from each subject and the areas of greatest intensity of temperature and glucose-uptake within the supraclavicular regions compared. Relationships between supraclavicular temperatures from IRT (TSCR) and the maximum rate of glucose uptake (MR(gluc)) from PET-CT were determined. Results Glucose uptake on MR(gluc)MIP was positively correlated with change in TSCR relative to a reference region (r² = 0.721; p=0.008). Spatial overlap between areas of maximal MR(gluc)MIP and maximal TSCR was 29.5±5.1%. Prolonged cooling to 60 minutes was associated with further TSCR rise compared with cooling to 10 minutes. Conclusions The supraclavicular hotspot identified on IRT closely corresponds to the area of maximal uptake on PET-CT-derived MR(gluc)MIP images. Greater increases in relative TSCR were associated with raised glucose uptake. IRT should now be considered a suitable method for measuring BAT activation, especially in populations where PET-CT is not feasible, practical or repeatable

Ligand-Specific Factors Influencing GLP-1 Receptor Post-Endocytic Trafficking and Degradation in Pancreatic Beta Cells.

The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, using biorthogonal labelling of GLP-1R to determine its localisation and degradation after treatment with GLP-1, exendin-4 and several further GLP-1R agonist peptides. We also characterised the effect of a rare GLP1R coding variant, T149M, and the role of endosomal peptidase endothelin-converting enzyme-1 (ECE-1), in GLP1R trafficking. Our data reveal how treatment with GLP-1 versus exendin-4 is associated with preferential GLP-1R targeting towards a recycling pathway. GLP-1, but not exendin-4, is a substrate for ECE-1, and the resultant propensity to intra-endosomal degradation, in conjunction with differences in binding affinity, contributes to alterations in GLP-1R trafficking behaviours and degradation. The T149M GLP-1R variant shows reduced signalling and internalisation responses, which is likely to be due to disruption of the cytoplasmic region that couples to intracellular effectors. These observations provide insights into how ligand- and genotype-specific factors can influence GLP-1R trafficking

Application of small molecule FPR1 antagonists in the treatment of cancers

YesThe formylpeptide receptor-1 (FPR1) is a member of the chemotactic GPCR-7TM formyl peptide receptor family, whose principle function is in trafficking of various leukocytes into sites of bacterial infection and inflammation. More recently, FPR1 has been shown to be expressed in different types of cancer and in this context, plays a significant role in their expansion, resistance and recurrence. ICT12035 is a selective and potent (30 nM in calcium mobilisation assay) small molecule FPR1 antagonist. Here, we demonstrate the efficacy of ICT12035, in a number of 2D and 3D proliferation and invasion in vitro assays and an in vivo model. Our results demonstrate that targeting FPR1 by a selective small molecule antagonist, such as ICT12035, can provide a new avenue for the treatment of cancers

Reversed Immunoglycomics Identifies α-Galactosyl-Bearing Glycotopes Specific for Leishmania major Infection

All healthy humans have high levels of natural anti-α-galactosyl (α-Gal) antibodies (elicited by yet uncharacterized glycotopes), which may play important roles in immunoglycomics: (a) potential protection against certain parasitic and viral zoonotic infections; (b) targeting of α-Gal-engineered cancer cells; (c) aiding in tissue repair; and (d) serving as adjuvants in α-Gal-based vaccines. Patients with certain protozoan infections have specific anti-α-Gal antibodies, elicited against parasite-derived α-Gal-bearing glycotopes. These glycotopes, however, remain elusive except for the well-characterized glycotope Galα1,3Galβ1,4GlcNAcα, expressed by Trypanosoma cruzi. The discovery of new parasitic glycotopes is greatly hindered by the enormous structural diversity of cell-surface glycans and the technical challenges of classical immunoglycomics, a top-down approach from cultivated parasites to isolated glycans. Here, we demonstrate that reversed immunoglycomics, a bottom-up approach, can identify parasite species-specific α-Gal-bearing glycotopes by probing synthetic oligosaccharides on neoglycoproteins. This method was tested here seeking to identify as-yet unknown glycotopes specific for Leishmania major, the causative agent of Old-World cutaneous leishmaniasis (OWCL). Neoglycoproteins decorated with synthetic α-Gal-containing oligosaccharides derived from L. major glycoinositolphospholipids served as antigens in a chemiluminescent enzyme-linked immunosorbent assay using sera from OWCL patients and noninfected individuals. Receiver-operating characteristic analysis identified Galpα1,3Galfβ and Galpα1,3Galfβ1,3Manpα glycotopes as diagnostic biomarkers for L. major-caused OWCL, which can distinguish with 100% specificity from heterologous diseases and L. tropica-caused OWCL. These glycotopes could prove useful in the development of rapid α-Gal-based diagnostics and vaccines for OWCL. Furthermore, this method could help unravel cryptic α-Gal-glycotopes of other protozoan parasites and enterobacteria that elicit the natural human anti-α-Gal antibodies

Call for emergency action to restore dietary diversity and protect global food systems in times of COVID-19 and beyond: Results from a cross-sectional study in 38 countries

Background: The COVID-19 pandemic has revealed the fragility of the global food system, sending shockwaves across countries' societies and economy. This has presented formidable challenges to sustaining a healthy and resilient lifestyle. The objective of this study is to examine the food consumption patterns and assess diet diversity indicators, primarily focusing on the food consumption score (FCS), among households in 38 countries both before and during the first wave of the COVID-19 pandemic. Methods: A cross-sectional study with 37 207 participants (mean age: 36.70 ± 14.79, with 77 % women) was conducted in 38 countries through an online survey administered between April and June 2020. The study utilized a pre-tested food frequency questionnaire to explore food consumption patterns both before and during the COVID-19 periods. Additionally, the study computed Food Consumption Score (FCS) as a proxy indicator for assessing the dietary diversity of households. Findings: This quantification of global, regional and national dietary diversity across 38 countries showed an increment in the consumption of all food groups but a drop in the intake of vegetables and in the dietary diversity. The household's food consumption scores indicating dietary diversity varied across regions. It decreased in the Middle East and North Africa (MENA) countries, including Lebanon (p < 0.001) and increased in the Gulf Cooperation Council countries including Bahrain (p = 0.003), Egypt (p < 0.001) and United Arab Emirates (p = 0.013). A decline in the household's dietary diversity was observed in Australia (p < 0.001), in South Africa including Uganda (p < 0.001), in Europe including Belgium (p < 0.001), Denmark (p = 0.002), Finland (p < 0.001) and Netherland (p = 0.027) and in South America including Ecuador (p < 0.001), Brazil (p < 0.001), Mexico (p < 0.0001) and Peru (p < 0.001). Middle and older ages [OR = 1.2; 95 % CI = [1.125–1.426] [OR = 2.5; 95 % CI = [1.951–3.064], being a woman [OR = 1.2; 95 % CI = [1.117–1.367], having a high education (p < 0.001), and showing amelioration in food-related behaviors [OR = 1.4; 95 % CI = [1.292–1.709] were all linked to having a higher dietary diversity. Conclusion: The minor to moderate changes in food consumption patterns observed across the 38 countries within relatively short time frames could become lasting, leading to a significant and prolonged reduction in dietary diversity, as demonstrated by our findings.Revisión por pare