Project description:Chronic inflammation has been proposed to contribute to the pathogenesis of diet-induced obesity. However, scarce therapeutic options are available to treat obesity and the associated immunometabolic complications. Glucocorticoids are routinely employed for the management of inflammatory diseases, but their pleiotropic nature leads to detrimental metabolic side effects. We developed a glucagon-like peptide-1 (GLP-1)-Dexamethasone co-agonist in which GLP-1 selectively delivers Dexamethasone to GLP-1 receptor-expressing cells. GLP-1-Dexamethasone lowers body weight up to 25% in obese mice by targeting the hypothalamic control of feeding and by increasing energy expenditure. This strategy reverses hypothalamic and systemic inflammation while improving glucose tolerance and insulin sensitivity. The selective preference for GLP-1 receptors bypasses deleterious effects of Dexamethasone on glucose handling, bone integrity, and hypothalamus-pituitary-adrenal axis activity. Thus, GLP-1-directed glucocorticoid pharmacology represents an efficacious therapy option for diet-induced immunometabolic derangements and the resulting obesity.
Project description:Impaired insulin secretion contributes to the pathogenesis of type 2 diabetes mellitus (T2DM). Treatment with the incretin hormone glucagon-like peptide-1 (GLP-1) potentiates insulin secretion and improves metabolic control in humans with T2DM. GLP-1 receptor-mediated signaling leading to insulin secretion occurs via cyclic AMP stimulated protein kinase A (PKA)- as well as guanine nucleotide exchange factor-mediated pathways. However, how these two pathways integrate and coordinate insulin secretion remains poorly understood. Here we show that these incretin-stimulated pathways converge at the level of snapin, and that PKA-dependent phosphorylation of snapin increases interaction among insulin secretory vesicle-associated proteins, thereby potentiating glucose-stimulated insulin secretion (GSIS). In diabetic islets with impaired GSIS, snapin phosphorylation is reduced, and expression of a snapin mutant, which mimics site-specific phosphorylation, restores GSIS. Thus, snapin is a critical node in GSIS regulation and provides a potential therapeutic target to improve ? cell function in T2DM.
Project description:BackgroundThe glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide-1 (GLP-1) receptors are considered complementary therapeutic targets for type 2 diabetes. Using recombinant membrane-tethered ligand (MTL) technology, the present study focused on defining optimized modulators of these receptors, as well as exploring how local anchoring influences soluble peptide function.Methodology/principal findingsSerial substitution of residue 7 in membrane-tethered GIP (tGIP) led to a wide range of activities at the GIP receptor, with [G(7)]tGIP showing enhanced efficacy compared to the wild type construct. In contrast, introduction of G(7) into the related ligands, tGLP-1 and tethered exendin-4 (tEXE4), did not affect signaling at the cognate GLP-1 receptor. Both soluble and tethered GIP and GLP-1 were selective activators of their respective receptors. Although soluble EXE4 is highly selective for the GLP-1 receptor, unexpectedly, tethered EXE4 was found to be a potent activator of both the GLP-1 and GIP receptors. Diverging from the pharmacological properties of soluble and tethered GIP, the newly identified GIP-R agonists, (i.e. [G(7)]tGIP and tEXE4) failed to trigger cognate receptor endocytosis. In an attempt to recapitulate the dual agonism observed with tEXE4, we conjugated soluble EXE4 to a lipid moiety. Not only did this soluble peptide activate both the GLP-1 and GIP receptors but, when added to receptor expressing cells, the activity persists despite serial washes.ConclusionsThese findings suggest that conversion of a recombinant MTL to a soluble membrane anchored equivalent offers a means to prolong ligand function, as well as to design agonists that can simultaneously act on more than one therapeutic target.
Project description:Efficacy of statin-based therapies in reducing cardiovascular mortality in individuals with CKD seems to diminish as eGFR declines. The strongest evidence supporting the cardiovascular benefit of statins in individuals with CKD was shown with ezetimibe plus simvastatin versus placebo. However, whether combination therapy or statin alone resulted in cardiovascular benefit is uncertain. Therefore, we estimated GFR in 18,015 individuals from the IMPROVE-IT (ezetimibe plus simvastatin versus simvastatin alone in individuals with cardiovascular disease and creatinine clearance >30 ml/min) and examined post hoc the relationship of eGFR with end points across treatment arms. For the primary end point of cardiovascular death, major coronary event, or nonfatal stroke, the relative risk reduction of combination therapy compared with monotherapy differed by eGFR (P=0.04). The difference in treatment effect was observed at eGFR≤75 ml/min per 1.73 m2 and most apparent at levels ≤60 ml/min per 1.73 m2 Compared with individuals receiving monotherapy, individuals receiving combination therapy with a baseline eGFR of 60 ml/min per 1.73 m2 experienced a 12% risk reduction (hazard ratio [HR], 0.88; 95% confidence interval [95% CI], 0.82 to 0.95); those with a baseline eGFR of 45 ml/min per 1.73 m2 had a 13% risk reduction (HR, 0.87; 95% CI, 0.78 to 0.98). In stabilized individuals within 10 days of acute coronary syndrome, combination therapy seemed to be more effective than monotherapy in individuals with moderately reduced eGFR (30-60 ml/min per 1.73 m2). Further studies examining potential benefits of combination lipid-lowering therapy in individuals with CKD are needed.
Project description:Although antibiotics treat bacteremia in inhalational anthrax, pathogenesis is mainly driven by bacterial exotoxins. Raxibacumab, an IgG1 monoclonal antibody, binds the protective antigen (PA) of Bacillus anthracis, thus blocking toxin effects and leading to improved survival in the rabbit and monkey models of inhalational anthrax. To assess raxibacumab's added benefit over levofloxacin (LVX) alone, rabbits surviving to 84 h after a challenge with 200 times the median (50%) lethal dose of B. anthracis spores were randomized to receive 3 daily intragastric LVX doses of 50 mg/kg of body weight, with the first LVX dose administered just prior to administration of a single intravenous dose of placebo or 40 mg/kg raxibacumab. The percentages of animals alive at 28 days following the last LVX dose were compared between the 2 treatment groups using a two-sided likelihood-ratio chi-square test. The 82% survival rate for the LVX-raxibacumab combination was higher than the 65% survival rate for LVX alone (P=0.0874). There were nearly 2-fold fewer deaths for the combination (7 deaths; n=39) than for LVX alone (13 deaths; n=37), and the survival time was prolonged for the combination (P=0.1016). Toxin-neutralizing-activity titers were similar for both treatment groups, suggesting that survivors in both groups were able to mount a toxin-neutralizing immune response. Microscopic findings considered consistent with anthrax were present in animals that died or became moribund on study in both treatment groups, and there were no anthrax-related findings in animals that survived. Overall, raxibacumab provided a meaningful benefit over antibiotic alone when administered late in the disease course.
Project description:ImportanceThe Inflation Reduction Act of 2022 authorizes Medicare to negotiate prices of top-selling drugs based on several factors, including therapeutic benefit compared with existing treatment options.ObjectiveTo determine the added therapeutic benefit of the 50 top-selling brand-name drugs in Medicare in 2020, as assessed by health technology assessment (HTA) organizations in Canada, France, and Germany.Design, setting, and participantsIn this cross-sectional study, publicly available therapeutic benefit ratings, US Food and Drug Administration documents, and the Medicare Part B and Part D prescription drug spending dashboards were used to determine the 50 top-selling single-source drugs used in Medicare in 2020 and to assess their added therapeutic benefit ratings through 2021.Main outcomes and measuresRatings from HTA bodies in Canada, France, and Germany were categorized as high (moderate or greater) or low (minor or no) added benefit. Each drug was rated based on its most favorable rating across countries, indications, subpopulations, and dosage forms. We compared the use and prerebate and postrebate (ie, net) Medicare spending between drugs with high vs low added benefit.ResultsForty-nine drugs (98%) received an HTA rating by at least 1 country; 22 of 36 drugs (61%) received a low added benefit rating in Canada, 34 of 47 in France (72%), and 17 of 29 in Germany (59%). Across countries, 27 drugs (55%) had a low added therapeutic rating, accounting for $19.3 billion in annual estimated net spending, or 35% of Medicare net spending on the 50 top-selling single-source drugs and 11% of total Medicare net prescription drug spending in 2020. Compared with those with high added benefit, drugs with a low added therapeutic rating were used by more Medicare beneficiaries (median 387 149 vs 44 869) and had lower net spending per beneficiary (median $992 vs $32 287).Conclusions and relevanceMany top-selling Medicare drugs received low added benefit ratings by the national HTA organizations of Canada, France, and Germany. When negotiating prices for these drugs, Medicare should ensure they are not priced higher than reasonable therapeutic alternatives.
Project description:We sought to improve lumbar spine bone mineral density (LS-BMD) in long-term survivors of childhood acute lymphoblastic leukemia (ALL) using calcium and cholecalciferol supplementation.This double-blind, placebo-controlled trial randomized 275 participants (median age, 17 [9-36.1] years) with age- and gender-specific LS-BMD Z-scores <0 to receive nutritional counseling with supplementation of 1,000 mg/day calcium and 800 International Unit cholecalciferol or placebo for 2 years. The primary outcome was change in LS-BMD assessed by quantitative computerized tomography (QCT) at 24 months. Linear regression models were employed to identify the baseline risk factors for low LS-BMD and to compare LS-BMD outcomes.Pre-randomization LS-BMD below the mean was associated with male gender (P = 0.0024), White race (P = 0.0003), lower body mass index (P < 0.0001), and cumulative glucocorticoid doses of ? 5,000 mg (P = 0.0012). One hundred eighty-eight (68%) participants completed the study; 77% adhered to the intervention. Mean LS-BMD change did not differ between survivors randomized to supplements (0.33 ± 0.57) or placebo (0.28 ± 0.56). Participants aged 9-13 years and those 22-35 years had the greatest mean increases in LS-BMD (0.50 ± 0.66 and 0.37 ± 0.23, respectively). Vitamin D insufficiency (serum 25[OH]D <30 ng/ml) found in 296 (75%), was not associated with LS-BMD outcomes (P = 0.78).Cholecalciferol and calcium supplementation provides no added benefit to nutritional counseling for improving LS-BMD among adolescent and young adult survivors of ALL (93% of whom had LS-BMD Z-scores above the mean at study entry).
Project description:ObjectiveCommon variants in the gene TCF7L2 confer the largest effect on the risk of type 2 diabetes. The present study was undertaken to increase our understanding of the mechanisms by which this gene affects type 2 diabetes risk.Research design and methodsEight subjects with risk-conferring TCF7L2 genotypes (TT or TC at rs7903146) and 10 matched subjects with wild-type genotype (CC) underwent 5-h oral glucose tolerance test (OGTT), isoglycemic intravenous glucose infusion, and graded glucose infusion (GGI). Mathematical modeling was used to quantify insulin-secretory profiles during OGTT and glucose infusion protocols. The incretin effect was assessed from ratios of the insulin secretory rates (ISR) during oral and isoglycemic glucose infusions. Dose-response curves relating insulin secretion to glucose concentrations were derived from the GGI.Resultsbeta-cell responsivity to oral glucose was 50% lower (47 +/- 4 vs. 95 +/- 15 x 10(9) min(-1); P = 0.01) in the group of subjects with risk-conferring TCF7L2 genotypes compared with control subjects. The incretin effect was also reduced by 30% (32 +/- 4 vs. 46 +/- 4%; P = 0.02) in the at-risk group. The lower incretin effect occurred despite similar glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) responses to oral glucose. The ISR response to intravenous glucose over a physiologic glucose concentration range (5-9 mmol/l) was similar between groups.ConclusionsThe TCF7L2 variant rs7903146 appears to affect risk of type 2 diabetes, at least in part, by modifying the effect of incretins on insulin secretion. This is not due to reduced secretion of GLP-1 and GIP but rather due to the effect of TCF7L2 on the sensitivity of the beta-cell to incretins. Treatments that increase incretin sensitivity may decrease the risk of type 2 diabetes.