Glucagon augments the secretion of FGF21 and GDF15 in MASLD by indirect mechanisms.

INTRODUCTION: Glucagon receptor agonism is currently explored for the treatment of obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). The metabolic effects of glucagon receptor agonism may in part be mediated by increases in circulating levels of Fibroblast Growth Factor 21 (FGF21) and Growth Differentiation Factor 15 (GDF15). The effect of glucagon agonism on FGF21 and GDF15 levels remains uncertain, especially in the context of elevated insulin levels commonly observed in metabolic diseases. METHODS: We investigated the effect of a single bolus of glucagon and a continuous infusion of glucagon on plasma concentrations of FGF21 and GDF15 in conditions of endogenous low or high insulin levels. The studies included individuals with overweight with and without MASLD, healthy controls (CON) and individuals with type 1 diabetes (T1D). The direct effect of glucagon on FGF21 and GDF15 was evaluated using our in-house developed isolated perfused mouse liver model. RESULTS: FGF21 and GDF15 correlated with plasma levels of insulin, but not glucagon, and their secretion was highly increased in MASLD compared with CON and T1D. Furthermore, FGF21 levels in individuals with overweight with or without MASLD did not increase after glucagon stimulation when insulin levels were kept constant. FGF21 and GDF15 levels were unaffected by direct stimulation with glucagon in the isolated perfused mouse liver. CONCLUSION: The glucagon-induced secretion of FGF21 and GDF15 is augmented in MASLD and may depend on insulin. Thus, glucagon receptor agonism may augment its metabolic benefits in patients with MASLD through enhanced secretion of FGF21 and GDF15.

Development of a glucagon sensitivity test in humans: Pilot data and the GLUSENTIC study protocol.

A physiological feedback system exists between hepatocytes and the alpha cells, termed the liver-alpha cell axis and refers to the relationship between amino acid-stimulated glucagon secretion and glucagon-stimulated amino acid catabolism. Several reports indicate that non-alcoholic fatty liver disease (NAFLD) disrupts the liver-alpha cell axis, because of impaired glucagon receptor signaling (glucagon resistance). However, no experimental test exists to assess glucagon resistance in humans. The objective was to develop an experimental test to determine glucagon sensitivity with respect to amino acid and glucose metabolism in humans. The proposed glucagon sensitivity test (comprising two elements: 1) i.v. injection of 0.2 mg glucagon and 2) infusion of mixed amino acids 331 mg/hour/kg) is based on nine pilot studies which are presented. Calculation of a proposed glucagon sensitivity index with respect to amino acid catabolism is also described. Secondly, we describe a complete study protocol (GLUSENTIC) according to which the glucagon sensitivity test will be applied in a cross-sectional study currently taking place. 65 participants including 20 individuals with a BMI 18.6-25 kg/m2, 30 individuals with a BMI ≥ 25-40 kg/m2, and 15 individuals with type 1 diabetes with a BMI between 18.6 and 40 kg/m2 will be included. Participants will be grouped according to their degree of hepatic steatosis measured by whole-liver magnetic resonance imaging (MRI). The primary outcome measure will be differences in the glucagon sensitivity index between individuals with and without hepatic steatosis. Developing a glucagon sensitivity test and index may provide insight into the physiological and pathophysiological mechanism of glucagon action and glucagon-based therapies.

Evaluation of the benefit of corticosteroid injection before exercise therapy in patients with osteoarthritis of the knee: a randomized clinical trial.

IMPORTANCE: Osteoarthritis (OA) of the knee is the most frequent form of arthritis and a cause of pain and disability. Combined nonpharmacologic and pharmacologic treatments are recommended as the optimal treatment approach, but no evidence supports the recommendation. OBJECTIVE: To assess the clinical benefits of an intra-articular corticosteroid injection given before exercise therapy in patients with OA of the knee. DESIGN, SETTING, AND PARTICIPANTS: We performed a randomized, blinded, placebo-controlled clinical trial evaluating the benefit of intra-articular corticosteroid injection vs placebo injection given before exercise therapy at an OA outpatient clinic from October 1, 2012, through April 2, 2014. The participants had radiographic confirmation of clinical OA of the knee, clinical signs of localized inflammation in the knee, and knee pain during walking (score >4 on a scale of 0 to 10). INTERVENTIONS: Participants were randomly allocated (1:1) to an intra-articular 1-mL injection of the knee with methylprednisolone acetate (Depo-Medrol), 40 mg/mL, dissolved in 4 mL of lidocaine hydrochloride (10 mg/mL) (corticosteroid group) or a 1-mL isotonic saline injection mixed with 4 mL of lidocaine hydrochloride (10 mg/mL) (placebo group). Two weeks after the injections, all participants started a 12-week supervised exercise program. MAIN OUTCOMES AND MEASURES: The primary outcome was change in the Pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire (range, 0-100; higher scores indicate greater improvement) at week 14. Secondary outcomes included the remaining KOOS subscales and objective measures of physical function and inflammation. Outcomes were measured at baseline, week 2 (exercise start), week 14 (exercise stop), and week 26 (follow-up). RESULTS: One hundred patients were randomized to the corticosteroid group (n = 50) or the placebo group (n = 50); 45 and 44 patients, respectively, completed the trial. The mean (SE) changes in the KOOS Pain subscale score at week 14 were 13.6 (1.8) and 14.8 (1.8) points in the corticosteroid and placebo groups, respectively, corresponding to a statistically insignificant mean difference of 1.2 points (95% CI, -3.8 to 6.2; P = .64). We found no statistically significant group differences in any of the secondary outcomes at any time point. CONCLUSIONS AND RELEVANCE: No additional benefit results from adding an intra-articular injection of 40 mg of corticosteroid before exercise in patients with painful OA of the knee. Further research is needed to establish optimal and potentially synergistic combinations of conservative treatments. TRIAL REGISTRATION: clinicaltrialsregister.eu Identifier: 2012-002607-18; clinicaltrials.gov Identifier: NCT01945749.