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Context The mechanisms underlying Roux-en-Y gastric bypass (RYGB) surgery-induced weight loss and the immediate postoperative beneficial metabolic effects associated with the operation remain uncertain. Enteroendocrine cell (EEC) secretory function has been proposed as a key factor in the marked metabolic benefits from RYGB surgery. Objective To identify novel gut-derived peptides with therapeutic potential in obesity and/or diabetes by profiling of EEC-specific molecular changes in obese patients following RYGB-induced weight loss. Subjects and Methods Genome-wide expression analysis was performed in isolated human small intestinal EECs obtained from 20 gut-biopsied obese subjects before and after RYGB. Targets of interest were profiled for preclinical and clinical metabolic effects. Results RYGB consistently increased expression levels of the inverse ghrelin receptor agonist, liver-expressed antimicrobial peptide 2 (LEAP2). A secreted endogenous LEAP2 fragment (LEAP238-47) demonstrated robust insulinotropic properties, stimulating insulin release in human pancreatic islets comparable to the gut hormone glucagon-like peptide-1. LEAP238-47 showed reciprocal effects on growth hormone secretagogue receptor (GHSR) activity, suggesting that insulinotropic action of the peptide may be directly linked to attenuation of tonic GHSR activity. The fragment was infused in healthy human individuals (n=10), but no glucoregulatory effect was observed in the chosen dose as compared to placebo. Conclusions Small intestinal LEAP2 expression was upregulated after RYGB. The corresponding circulating LEAP238-47 fragment demonstrated strong insulinotropic action in vitro, but failed to elicit glucoregulatory effects in healthy human subjects.

Non-alcoholic steatohepatitis (NASH) has emerged as a major challenge for public health because of high global prevalence and lack of evidence-based therapies. Most animal models of NASH lack sufficient validation regarding disease progression and pharmacological treatment. The Gubra-Amylin NASH (GAN) diet-induced obese (DIO) mouse demonstrate clinical translatability with respect to disease etiology and hallmarks of NASH. This study aimed to evaluate disease progression and responsiveness to clinically effective interventions in GAN DIO-NASH mice. Disease phenotyping was performed in male C57BL/6J mice fed the GAN diet high in fat, fructose, and cholesterol for 28-88 weeks. GAN DIO-NASH mice with biopsy-confirmed NASH and fibrosis received low-caloric dietary intervention, semaglutide (30 nmol/kg/day, s.c.) or lanifibranor (30 mg/kg/day, p.o.) for 8 and 12 weeks, respectively. Within-subject change in nonalcoholic fatty liver disease (NAFLD) Activity Score (NAS) and fibrosis stage was evaluated using automated deep learning-based image analysis. GAN DIO-NASH mice showed clear and reproducible progression in NASH, fibrosis stage, and tumor burden with high incidence of hepatocellular carcinoma. Consistent with clinical trial outcomes, semaglutide and lanifibranor improved NAS, whereas only lanifibranor induced regression in the fibrosis stage. Dietary intervention also demonstrated substantial benefits on metabolic outcomes and liver histology. Differential therapeutic efficacy of semaglutide, lanifibranor, and dietary intervention was supported by quantitative histology, RNA sequencing, and blood/liver biochemistry. In conclusion, the GAN DIO-NASH mouse model recapitulates various histological stages of NASH and faithfully reproduces histological efficacy profiles of compounds in advanced clinical development for NASH. Collectively, these features highlight the utility of GAN DIO-NASH mice in preclinical drug development.

Aims/hypothesis Glucose-dependent insulinotropic polypeptide (GIP) has been proposed to exert insulin-independent effects on lipid and bone metabolism. We investigated the effect of a 6-day s.c. GIP infusion on circulating lipids, white adipose tissue (WAT), brown adipose tissue (BAT), hepatic fat content, inflammatory markers, respiratory exchange ratio (RER), and bone homeostasis in patients with type 1 diabetes. Methods In a randomized, placebo-controlled, double-blind, crossover study, 20 men with type 1 diabetes underwent a 6-day continuous s.c. infusion with GIP (6 pmol/kg/min) and placebo (saline), with an interposed 7-day washout period. Results During GIP infusion, participants (26 ± 8 years [mean ± SD]; BMI 23.8 ± 1.8 kg/m2; HbA1c 51 ± 10 mmol/mol [6.8 ± 3.1%]) experienced transiently increased circulating concentrations of NEFA (p = 0.0005), decreased RER (p = 0.009), indication of increased fatty acid β-oxidation, and decreased levels of the bone resorption marker C-terminal telopeptide (p = 0.000072) compared to placebo. After six days of GIP infusion, hepatic fat content was increased by 12.6% (p = 0.007) and supraclavicular skin temperature, a surrogate indicator of BAT activity, was increased by 0.29°C (p < 0.000001) compared to placebo. WAT transcriptomic profile as well as circulating lipid species, proteome, markers of inflammation, and bone homeostasis were unaffected. Conclusions/interpretation Six days s.c. GIP infusion in men with type 1 diabetes transiently decreased bone resorption and increased NEFA and β-oxidation. Further, hepatic fat content, and supraclavicular skin temperature were increased without affecting WAT transcriptomics, the circulating proteome, lipids, or inflammatory markers.

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