Liraglutide and Naringenin relieve depressive symptoms in mice by enhancing Neurogenesis and reducing inflammation

Depression is a debilitating mental disease that negatively impacts individuals' lives and society. Novel hypotheses have been recently proposed to improve our understanding of depression pathogenesis. Impaired neuroplasticity and upregulated neuro-inflammation add-on to the disturbance in monoamine neurotransmitters and therefore require novel anti-depressants to target them simultaneously. Recent reports demonstrate the antidepressant effect of the anti-diabetic drug liraglutide. Similarly, the natural flavonoid naringenin has shown both anti-diabetic and anti-depressant effects. However, the neuro-pharmacological mechanisms underlying their actions remain understudied. The study aims to evaluate the antidepressant effects and neuroprotective mechanisms of liraglutide, naringenin or a combination of both. Depression was induced in mice by administering dexamethasone (32 mcg/kg) for seven consecutive days. Liraglutide (200 mcg/kg), naringenin (50 mg/kg) and a combination of both were administered either simultaneously or after induction of depression for twenty-eight days. Behavioral and molecular assays were used to assess the progression of depressive symptoms and biomarkers. Liraglutide and naringenin alone or in combination alleviated the depressive behavior in mice, manifested by decrease in anxiety, anhedonia, and despair. Mechanistically, liraglutide and naringenin improved neurogenesis, decreased neuroinflammation and comparably restored the monoamines levels to that of the reference drug escitalopram. The drugs protected mice from developing depression when given simultaneously with dexamethasone. Collectively, the results highlight the usability of liraglutide and naringenin in the treatment of depression in mice and emphasize the different pathways that contribute to the pathogenesis of depression.

Liraglutide attenuates angiotensin II-induced aortic dissection and aortic aneurysm via inhibiting M1 macrophage polarization in APOE -/- mice

BACKGROUND

Aortic Aneurysm and Dissection (AAD) are severe cardiovascular conditions with potentially lethal consequences such as aortic rupture. Existing studies suggest that liraglutide, a long-acting glucagon-like peptide receptor (GLP-1R) agonist, offers protective benefits across various cardiovascular diseases. However, the efficacy of liraglutide in mitigating AAD development is yet to be definitively elucidated.

METHODS

Ang II (Angiotension II) infusion of APOE-/- mouse model with intraperitoneal injection of liraglutide (200 μg/kg) to study the role of GLP-1R in AAD formation. Bone Marrow Derived Macrophages (BMDM) and Raw264.7 were incubated with LPS, liraglutide, exendin 9-39 or LY294002 alone or in combination. SMC phenotype switching was examined in a macrophage and vascular smooth muscle cell (VSMC) co-culture system. An array of analytical methods, including Western Blot, Immunofluorescence Staining, Enzyme-LinkedImmunosorbent Assay, Real-Time Quantitative Polymerase Chain Reaction, RNA-seq, and so on were employed.

RESULTS

Our investigation revealed a significant increase in M1 macrophage polarization and GLP-1R expression in aortas of AD patients and Ang II-induced AAD APOE-/- mice. Administering liraglutide in APOE-/- mice notably reduced Ang II-induced AAD incidence and mortality. It was found that liraglutide inhibits M1 macrophage polarization primarily via GLP-1R activation, and subsequently modulates vascular smooth muscle cell phenotypic switching was the primary mechanism. RNA-Seq and subsequent KEGG enrichment analysis identified CXCL3, regulated by the PI3K/AKT signaling pathway, as a key element in liraglutide's modulation of M1 macrophage polarization.

CONCLUSION

Our study found liraglutide exhibits protective effects against AAD by modulating M1 macrophage polarization, suppressing CXCL3 expression through the PI3K/AKT signaling pathway. This makes it a promising therapeutic target for AAD, offering a new avenue in AAD management.

Liraglutide prevents cellular senescence in human retinal endothelial cells (HRECs) mediated by SIRT1: an implication in diabetes retinopathy

Diabetes mellitus (DM) is a chronic metabolic disorder affecting millions of people worldwide, characterized by dysregulated glucose homeostasis and hyperglycemia. Diabetic retinopathy (DR) is one of the serious multisystemic complications. Aging is an important risk factor for DR. Endothelial sirtuin 1 (SIRT1) plays an important role in regulating the pathophysiology of glucose metabolism, cellular senescence, and aging. Liraglutide, an analog of Glucagon-like peptide 1 (GLP-1), has been widely used in the treatment of DM. However, the effects of Liraglutide on DR are less reported. Here, we investigated whether treatment with Liraglutide has beneficial effects on high glucose (HG)-induced injury in human retinal microvascular endothelial cells (HRECs). First, we found that exposure to HG reduced the expression of glucagon-like peptide 1 receptor 1 (GLP-1R). Additionally, Liraglutide ameliorated HG-induced increase in the expression of vascular endothelial growth factor-A (VEGF-A) and interleukin 6 (IL-6). Importantly, Liraglutide ameliorated cellular senescence and increased telomerase activity in HG-challenged HRECs. Liraglutide also reduced the levels of p53 and p21. Mechanistically, Liraglutide restored the expression of SIRT1 against HG. In contrast, the knockdown of SIRT1 abolished the protective effects of Liraglutide in cellular senescence of HRECs. Our findings suggest that Liraglutide might possess a benefit on DR mediated by SIRT1.

Liraglutide versus pramlintide in protecting against cognitive function impairment through affecting PI3K/AKT/GSK-3β/TTBK1 pathway and decreasing Tau hyperphosphorylation in high-fat diet- streptozocin rat model

The American Diabetes Association guidelines (2021) confirmed the importance of raising public awareness of diabetes-induced cognitive impairment, highlighting the links between poor glycemic control and cognitive impairment. The characteristic brain lesions of cognitive dysfunction are neurofibrillary tangles (NFT) and senile plaques formed of amyloid-β deposition, glycogen synthase kinase 3 beta (GSK3β), and highly homologous kinase tau tubulin kinase 1 (TTBK1) can phosphorylate Tau proteins at different sites, overexpression of these enzymes produces extensive phosphorylation of Tau proteins making them insoluble and enhance NFT formation, which impairs cognitive functions. The current study aimed to investigate the potential contribution of liraglutide and pramlintide in the prevention of diabetes-induced cognitive dysfunction and their effect on the PI3K/AKT/GSK-3β/TTBK1 pathway in type 2 diabetic (T2D) rat model. T2D was induced by administration of a high-fat diet for 10 weeks, then injection of a single dose of streptozotocin (STZ); treatment was started with either pramlintide (200 μg/kg/day sc) or liraglutide (0.6 mg/kg/day sc) for 6 weeks in addition to the HFD. At the end of the study, cognitive functions were assessed by novel object recognition and T-maze tests. Then, rats were sacrificed for biochemical and histological assessment of the hippocampal tissue. Both pramlintide and liraglutide treatment revealed equally adequate control of diabetes, prevented the decline in memory function, and increased PI3K/AKT expression while decreasing GSK-3β/TTBK1 expression; however, liraglutide significantly decreased the number of Tau positive cells better than pramlintide did. This study confirmed that pramlintide and liraglutide are promising antidiabetic medications that could prevent associated cognitive disorders in different mechanisms.

Endocannabinoid-related molecules predict the metabolic efficacy of GLP-1 receptor agonism in humans with obesity

OBJECTIVE

N-acylethanolamines (NAEs) include endocannabinoid (EC) and EC-related molecules that impact the anti-obesity and anti-diabetic efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RA) in animal studies. However, the clinical relevance of these findings remains to be determined. Here, we tested whether GLP-1RA treatment affects circulating NAE levels and whether NAEs may predict the efficacy of GLP-1RA treatment in humans with obesity undergoing weight loss maintenance.

MATERIALS AND METHODS

We profiled plasma levels of NAEs in participants with obesity undergoing weight loss maintenance with (n = 23)/or without (n = 20) treatment with the GLP-1RA liraglutide. NAE levels were measured at three different time points: before the start of the study, at the end of the diet-induced weight loss, and after 52-weeks treatment. Linear regression analyses were used to investigate whether pharmacological responses could be predicted by NAEs levels.

RESULTS

Liraglutide treatment reduced plasma concentrations of the NAE and oleoyl-ethanolamide (OEA), without altering arachidonoyl-ethanolamide (AEA) levels and palmitoyl-ethanolamide (PEA) levels. High pre-treatment levels of OEA were predictive of superior compound-mediated effects on fasting insulin and triglyceride levels. High pre-treatment PEA and AEA levels were also predictive of superior Liraglutide-mediated effects on triglyceride levels.

CONCLUSIONS

Our data suggests that specific NAEs such as OEA and AEA are promising biomarkers of GLP-1RA metabolic efficacy in humans with obesity during weight loss maintenance. Plasma profiling of EC-related molecules may be a promising strategy to tailor GLP-1R-based therapies to individual needs in obesity and diabetes management.

The GLP-1R as a model for understanding and exploiting biased agonism in next-generation medicines

The glucagon-like peptide 1 receptor (GLP-1R) is a class B G protein-coupled receptor (GPCR) that emerged as a pharmacologic target in cardiometabolic disease, including diabetes and obesity, over 30 years ago. The subsequent widespread clinical use of GLP-1R agonists, including exenatide, liraglutide, and semaglutide, has made the GLP-1R a preeminent model for understanding basic GPCR biology, including the emergent field of biased agonism. Recent data demonstrate that the dual GLP-1R/glucose dependent insulinotropic polypeptide receptor (GIPR) agonist tirzepatide exhibits a biased signaling profile characterized by preferential Gαs activation over β-arrestin recruitment, which appears to contribute to its insulinotropic and body-weight reducing effects in preclinical models. This constitutes a major finding in which nuanced, mechanistic receptor signaling dynamics in vitro mediate real-world clinical differentiation within a drug class. Because of the striking bench-top-to-bed side relevance of this biased signaling phenomenon, we have undertaken a review of the emerging data detailing biased agonism at the GLP-1R. In this review, we introduce the core concept of biased agonism followed by a detailed consideration of the key mechanisms, including ligand-mediated bias, receptor-mediated bias, and systems/cell-type bias. Current industry programs are largely, if not entirely, focused on developing biased ligands, and so we have dedicated a section of the review to a brief meta-analysis of compounds reported to drive biased signaling, with a consideration of the structural determinants of receptor-ligand interactions. In this work, we aim to assess the current knowledge regarding signaling bias at the GLP-1R and how these ideas might be leveraged in future optimization.

Glucagon-Like Peptide-1 Receptor Agonists in Post-bariatric Surgery Patients: A Systematic Review and Meta-analysis

BACKGROUND

A significant number of patients face the issue of weight gain (WG) or inadequate weight loss (IWL) post-bariatric surgery for obesity. Several studies have been published evaluating the role of glucagon-like peptide-1 receptor agonists (GLP1RA) for weight loss post-bariatric surgery. However, no systematic review and meta-analysis (SRM) till date has evaluated the efficacy, safety and tolerability of GLP1RA in this clinical scenario. Hence, this SRM aimed to address this knowledge gap.

METHODS

Databases were searched for randomized controlled trials (RCTs), case-control, cohort and observational studies involving use of GLP1RA in the intervention arm post-bariatric surgery. Primary outcome was weight loss post at least 3 months of therapy. Secondary outcomes were evaluation of body composition parameters, total adverse events (TAEs) and severe adverse events (SAEs).

RESULTS

From initially screened 1759 articles, 8 studies (557 individuals) were analysed. Compared to placebo, patients receiving liraglutide had significantly greater weight loss after 6-month therapy [MD - 6.0 kg (95% CI, - 8.66 to - 3.33); P < 0.001; I2 = 79%]. Compared to liraglutide, semaglutide had significantly greater percent reduction in body weight after 6-month [MD - 2.57% (95% CI, - 3.91 to - 1.23); P < 0.001; I2 = 0%] and 12-month [MD - 4.15% (95% CI, - 6.96 to - 1.34); P = 0.004] therapy. In study by Murvelashvili et al. (2023), after 12-month therapy, semaglutide had significantly higher rates of achieving > 15% [OR 2.15 (95% CI, 1.07-4.33); P = 0.03; n = 207] and > 10% [OR 2.10 (95% CI, 1.19-3.71); P = 0.01; n = 207] weight loss. A significant decrease in fat mass [MD - 4.78 kg (95% CI, - 7.11 to - 2.45); P < 0.001], lean mass [MD - 3.01 kg (95% CI, - 4.80 to - 1.22); P = 0.001] and whole-body bone mineral density [MD - 0.02 kg/m2 (95% CI, - 0.04 to - 0.00); P = 0.03] was noted with liraglutide.

CONCLUSION

Current data is encouraging regarding use of GLP1RAs for managing WG or IWL post-bariatric surgery. Deterioration of bone health and muscle mass remains a concern needing further evaluation.

TRIAL REGISTRATION

The predefined protocol has been registered in PROSPERO having registration number of CRD42023473991.

Dietary salt promotes cognition impairment through GLP-1R/mTOR/p70S6K signaling pathway

Dietary salt has been associated with cognitive impairment in mice, possibly related to damaged synapses and tau hyperphosphorylation. However, the mechanism underlying how dietary salt causes cognitive dysfunction remains unclear. In our study, either a high-salt (8%) or normal diet (0.5%) was used to feed C57BL/6 mice for three months, and N2a cells were cultured in normal medium, NaCl medium (80 mM), or NaCl (80 mM) + Liraglutide (200 nM) medium for 48 h. Cognitive function in mice was assessed using the Morris water maze and shuttle box test, while anxiety was evaluated by the open field test (OPT). Western blotting (WB), immunofluorescence, and immunohistochemistry were utilized to assess the level of Glucagon-like Peptide-1 receptor (GLP-1R) and mTOR/p70S6K pathway. Electron microscope and western blotting were used to evaluate synapse function and tau phosphorylation. Our findings revealed that a high salt diet (HSD) reduced the level of synaptophysin (SYP) and postsynaptic density 95 (PSD95), resulting in significant synaptic damage. Additionally, hyperphosphorylation of tau at different sites was detected. The C57BL/6 mice showed significant impairment in learning and memory function compared to the control group, but HSD did not cause anxiety in the mice. In addition, the level of GLP-1R and autophagy flux decreased in the HSD group, while the level of mTOR/p70S6K was upregulated. Furthermore, liraglutide reversed the autophagy inhibition of N2a treated with NaCl. In summary, our study demonstrates that dietary salt inhibits the GLP-1R/mTOR/p70S6K pathway to inhibit autophagy and induces synaptic dysfunction and tau hyperphosphorylation, eventually impairing cognitive dysfunction.

Liraglutide ameliorates delirium-like behaviors of aged mice undergoing cardiac surgery by mitigating microglia activation via promoting mitophagy

OBJECTIVE

Postoperative delirium (POD) is a prevalent complication in cardiac surgery patients, particularly the elderly, with neuroinflammation posited as a crucial contributing factor. We investigated the prophylactic effects of liraglutide, a GLP-1 analog, on delirium-like behaviors in aged mice undergoing cardiac surgery and explored the underlying mechanisms focusing on neuroinflammation, mitochondrial dysfunction, and synaptic plasticity.

METHODS

Using a cardiac ischemia-reperfusion animal model to mimic cardiac surgery, we assessed delirium-like behaviors, microglial activation, NLRP3 inflammasome activation, mitophagy, synaptic engulfment, and synaptic plasticity.

RESULTS

Cardiac surgery triggered delirium-like behaviors, concomitant with heightened microglial and NLRP3 inflammasome activation and impaired mitochondrial function and synaptic plasticity. Pretreatment with liraglutide ameliorated these adverse outcomes. Mechanistically, liraglutide enhanced mitophagy, thereby inhibiting NLRP3 inflammasome activation and subsequent microglial activation. Furthermore, liraglutide counteracted surgery-induced synaptic loss and impairment of synaptic plasticity.

CONCLUSION

Liraglutide exerts protective effects against delirium-like behaviors in aged mice post-cardiac surgery, potentially through bolstering microglia mitophagy, curtailing neuroinflammation, and preserving synaptic integrity. This highlights the potential of liraglutide as a promising perioperative strategy for delirium prevention in cardiac surgery patients.

Liraglutide Reduces Alcohol Consumption, Anxiety, Memory Impairment, and Synapse Loss in Alcohol Dependent Mice

Glucagon-like peptide 1 (GLP-1) analogues have been commercialized for the management of type 2 diabetes. Recent studies have underscored GLP-1's role as a modulator of alcohol-related behavior. However, the role of the GLP-1 analogue liraglutide on alcohol-withdrawal responses have not been fully elucidated. Liraglutide binds to the G-protein-coupled receptor and activates an adenylyl cyclase and the associated classic growth factor signaling pathway, which acts growth factor-like and neuroprotective properties. The underlying neurobiological mechanisms of liraglutide on alcohol withdrawal remains unknown. This study endeavored to explore the effects of liraglutide on the emotion and memory ability of alcohol-withdrawal mice, and synaptic morphology in the medial prefrontal cortex (mPFC) and the hippocampus (HP), and thus affects the relapse-like drinking of alcohol-withdrawal mice. The alcohol-withdrawal group was reintroduced to a 20% v/v alcohol and water through the two-bottle choice for four consecutive days, a period referred to as alcohol re-drinking. Male C57BL/6J mice were exposed to a regimen of 20% alcohol and water for a duration of 6 weeks. This regimen established the two-bottle choice model of alcohol exposure. Learning capabilities, memory proficiency, and anxiety-like behavior were evaluated using the Morris water maze, open field, and elevated plus maze paradigms. Furthermore, synaptic morphology and the levels of synaptic transport-related proteins were assessed via Golgi staining and Western Blot analysis after a two-week alcohol deprivation period. Alcohol re-drinking of alcohol-withdrawal mice was also evaluated using a two-bottle choice paradigm. Our findings indicate that liraglutide can substantially decrease alcohol consumption and preference (p < 0.05) in the alcohol group and enhance learning and memory performance (p < 0.01), as well as alleviate anxiety-like behavior (p < 0.01) of alcohol-withdrawal mice. Alcohol consumption led to a reduction in dendritic spine density in the mPFC and HP, which was restored to normal levels by liraglutide (p < 0.001). Furthermore, liraglutide was found to augment the levels of synaptic transport-related proteins in mice subjected to alcohol withdrawal (p < 0.01). The study findings corroborate that liraglutide has the potential to mitigate alcohol consumption and ameliorate the memory impairments and anxiety induced by alcohol withdrawal. The therapeutic efficacy of liraglutide might be attributed to its role in counteracting synapse loss in the mPFC and HP regions and thus prevented relapse-like drinking in alcohol-withdrawal mice.

Longitudinal Effects of Glucose-Lowering Medications on β-Cell Responses and Insulin Sensitivity in Type 2 Diabetes: The GRADE Randomized Clinical Trial

OBJECTIVE

To compare the long-term effects of glucose-lowering medications (insulin glargine U-100, glimepiride, liraglutide, and sitagliptin) when added to metformin on insulin sensitivity and β-cell function.

RESEARCH DESIGN AND METHODS

In the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study (GRADE) cohort with type 2 diabetes (n = 4,801), HOMA2 was used to estimate insulin sensitivity (HOMA2-%S) and fasting β-cell function (HOMA2-%B) at baseline and 1, 3, and 5 years on treatment. Oral glucose tolerance test β-cell responses (C-peptide index [CPI] and total C-peptide response [incremental C-peptide/incremental glucose over 120 min]) were evaluated at the same time points. These responses adjusted for HOMA2-%S in regression analysis provided estimates of β-cell function.

RESULTS

HOMA2-%S increased from baseline to year 1 with glargine and remained stable thereafter, while it did not change from baseline in the other treatment groups. HOMA2-%B and C-peptide responses were increased to variable degrees at year 1 in all groups but then declined progressively over time. At year 5, CPI was similar between liraglutide and sitagliptin, and higher for both than for glargine and glimepiride [0.80, 0.87, 0.74, and 0.64 (nmol/L)/(mg/dL) * 100, respectively; P < 0.001], while the total C-peptide response was greatest with liraglutide, followed in descending order by sitagliptin, glargine, and glimepiride [1.54, 1.25, 1.02, and 0.87 (nmol/L)/(mg/dL) * 100, respectively, P < 0.001]. After adjustment for HOMA2-%S to obtain an estimate of β-cell function, the nature of the change in β-cell responses reflected those in β-cell function.

CONCLUSIONS

The differential long-term effects on insulin sensitivity and β-cell function of four different glucose-lowering medications when added to metformin highlight the importance of the loss of β-cell function in the progression of type 2 diabetes.

Liraglutide improved the reproductive function of obese mice by upregulating the testicular AC3/cAMP/PKA pathway

BACKGROUND

The incidence of male reproductive dysfunction is increasing annually, and many studies have shown that obesity can cause severe harm to male reproductive function. The mechanism of male reproductive dysfunction caused by obesity is unclear, and there is no ideal treatment. Identification of effective therapeutic drugs and elucidation of the molecular mechanism involved in male reproductive health are meaningful. In this study, we investigated the effects of the GLP-1 receptor agonist liraglutide on sex hormones, semen quality, and testicular AC3/cAMP/PKA levels in high-fat-diet-induced obese mice.

METHODS

Obese mice and their lean littermates were treated with liraglutide or saline for 12 weeks. Body weight was measured weekly. Fasting blood glucose (FBG) was measured using a blood glucose test strip. The serum levels of insulin (INS), luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), free testosterone (F-TESTO), estradiol (E2), and sex hormone binding globulin (SHBG) were detected using ELISA. The sperm morphology and sperm count were observed after Pap staining. The mRNA and protein expression levels of testicular GLP-1R and AC3 were measured by RT-qPCR and Western blot, respectively. Testicular cAMP levels and PKA activity were detected using ELISA.

RESULTS

Liraglutide treatment can decrease body weight, FBG, INS, HOMA-IR, E2 and SHBG levels; increase LH, FSH, T, and F-TESTO levels; increase sperm count; decrease the sperm abnormality rate; and increase GLP-1R and AC3 expression levels and cAMP levels and PKA activity in testicular tissue.

CONCLUSIONS

Liraglutide can improve the sex hormone levels and semen quality of obese male mice. In addition to its weight loss effect, liraglutide can improve the reproductive function of obese male mice, which may also be related to the upregulation of AC3/cAMP/PKA pathway in the testis. This work lays the groundwork for future clinical studies.

Effect of liraglutide on cardiac function in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of double-blind, randomized, placebo-controlled trials

BACKGROUND

Liraglutide widely utilized in type 2 diabetes treatment, has elicited conflicting findings regarding its impact on cardiac function in patients with this condition. Therefore, The objective of this study was to conduct a meta-analysis of randomized controlled trials (RCTs) to evaluate the effects of liraglutide on cardiac function in patients diagnosed with type 2 diabetes.

METHODS

We identified double-blind randomized trials assessing the effects of liraglutide compared to placebo on cardiac function in patients with type 2 diabetes. Data were synthesized with the fixed-effect models to generate standard mean differences (SMDs) with 95% confidence intervals (CIs) of each outcome for liraglutide versus placebo. The risk of bias would be assessed according to the Cochrane Risk of Bias Tool, while meta-analysis would be conducted using Revman 5.3.0 software. The evidence was graded based on the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

The meta-analysis encompassed 5 RCTs including 220 participants. Results revealed that liraglutide exhibited significant enhancements in left ventricular ejection fraction [SMD = -0.38, 95%CI(-0.70, -0.06), P = .02], cardiac index [SMD = -1.05, 95%CI(-1.52, -0.59), P < .0001], stroke volume [SMD = -0.67, 95%CI(-1.02, -0.32), P = .0002] and early diastolic filling velocity/late atrial filling velocity ratio [SMD = -0.52, 95%CI(-0.82, -0.22), P = .0006]. However, no statistically significant impact on cardiac output [SMD = -0.20, 95%CI(-0.53, 0.14), P = .26], early diastolic filling velocity/early diastolic annular velocity (E/Ea) ratio [SMD = -0.34, 95%CI(-0.75, 0.06), P = .10] and early diastolic filling velocity/early diastolic mitral annular velocity ratio [SMD = 0.21, 95%CI(-0.15, 0.56), P = .25] was observed. The Grading of Recommendations Assessment, Development and Evaluation evidence quality ratings indicated that all the outcome measures included in this study were evaluated as having low and very low quality.

CONCLUSION

The available evidence suggested that liraglutide may exert a favorable impact on cardiac function in patients with type 2 diabetes. Consequently, the utilization of liraglutide as a preventive measure against heart failure incidents in individuals with type 2 diabetes represents a promising strategy. However, robust evidence support requires the conduct of large-scale, multicenter high-quality RCTs.

Comparing the effects of empagliflozin and liraglutide on lipid metabolism and intestinal microflora in diabetic mice

Background and Objectives

Recent studies have shown that the imbalance of intestinal flora is related to the occurrence and progression of diabetic nephropathy (DN) and can affect lipid metabolism. Sodium-dependent glucose transporters 2 (SGLT2) inhibitor and glucagon-like peptide-1 (GLP-1) receptor agonist are commonly used hypoglycemic drugs and have excellent renal safety. The purpose of this study was to compare the protective effects of empagliflozin and liraglutide on kidneys, lipid metabolism, and intestinal microbiota in diabetic mice.

Methods

We established a mouse model of type two diabetes by feeding rats a high-fat diet (HFD) followed by an intraperitoneal injection of STZ. The mice were randomly divided into groups: normal control (NC), diabetic model (DM), liraglutide treatment (LirT), empagliflozin treatment (EmpT), and liraglutide combined with empagliflozin treatment (Emp&LirT) groups. Blood glucose, lipids, creatinine, and uric acid, as well as urinary nitrogen and albumin levels were measured. The renal tissues were subjected to HE, PAS and Masson's staining. These parameters were used to evaluate renal function and histopathological changes in mice. Mice feces were also collected for 16sRNA sequencing to analyze the composition of the intestinal flora.

Results

All the indexes related to renal function were significantly improved after treatment with drugs. With respect to lipid metabolism, both drugs significantly decreased the serum triglyceride levels in diabetic mice, but the effect of liraglutide on reducing serum cholesterol was better than that of empagliflozin. However, empagliflozin had a better effect on the reduction of low-density lipoproteins (LDL). The two drugs had different effects on intestinal flora. At the phylum level, empagliflozin significantly reduced the ratio of Firmicutes to Bacteroidota, but no effect was seen with liraglutide. At the genus level, both of them decreased the number of Helicobacter and increased the number of Lactobacillus. Empagliflozin also significantly increased the abundance of Muribaculaceae, Muribaculum, Olsenella, and Odoribacter, while liraglutide significantly increased that of Ruminococcus.

Conclusion

Liraglutide and empagliflozin were both able to improve diabetes-related renal injury. However, the ability of empagliflozin to reduce LDL was better compared to liraglutide. In addition, their effects on the intestine bacterial flora were significantly different.

An oncolytic vaccinia virus encoding hyaluronidase reshapes the extracellular matrix to enhance cancer chemotherapy and immunotherapy

BACKGROUND

The redundant extracellular matrix (ECM) within tumor microenvironment (TME) such as hyaluronic acid (HA) often impairs intratumoral dissemination of antitumor drugs. Oncolytic viruses (OVs) are being studied extensively for cancer therapy either alone or in conjunction with chemotherapy and immunotherapy. Here, we designed a novel recombinant vaccinia virus encoding a soluble version of hyaluronidase Hyal1 (OVV-Hyal1) to degrade the HA and investigated its antitumor effects in combination with chemo drugs, polypeptide, immune cells, and antibodies.

METHODS

We constructed a recombinant oncolytic vaccinia virus encoding the hyaluronidase, and investigated its function in remodeling the ECM of the TME, the antitumor efficacy both in vitro and in several murine solid tumors either alone, or in combination with chemo drugs including doxorubicin and gemcitabine, with polypeptide liraglutide, with immune therapeutics such as PD-L1/PD-1 blockade, CD47 antibody, and with CAR-T cells.

RESULTS

Compared with control OVV, intratumoral injection of OVV-Hyal1 showed superior antitumor efficacies in a series of mouse subcutaneous tumor models. Moreover, HA degradation by OVV-Hyal1 resulted in increased intratumoral dissemination of chemo drugs, infiltration of T cells, NK cells, macrophages, and activation of CD8+ T cells. When OVV-Hyal1 was combined with some antitumor therapeutics, for example, doxorubicin, gemcitabine, liraglutide, anti-PD-1, anti-CD47 blockade, or CAR-T cells, more profound therapeutic outcomes were obtained.

CONCLUSIONS

OVV-Hyal1 effectively degrades HA to reshape the TME, therefore overcoming some major hurdles in current cancer therapy, such as limited OVs spread, unfavored dissemination of chemo drugs, polypeptides, antibodies, and insufficient infiltration of effector immune cells. OVV-Hyal1 holds the promise to improve the antitumor outcomes of current cancer therapeutics.

The impact of GLP-1 receptor agonist liraglutide on blood pressure profile, hydration, natriuresis in diabetic patients with severely impaired kidney function

Chronic treatment with GLP-1R agonists may moderately lower blood pressure due to increased natriuresis and RAAS inhibition. Short-term effect of these drugs on blood pressure may be opposite and its mechanism remains unclear. We investigated the effect of a single dose of liraglutide on diurnal blood pressure profile, natriuresis, hydration and serum concentration of renin, aldosterone and atrial natriuretic peptide (ANP) in diabetic kidney disease (DKD). 17 patients with eGFR < 30 ml/min/1.73 m2 and 17 with > 60 ml/min/1.73 m2 received in a random order a single subcutaneous dose 1.2 mg liraglutide and placebo with subsequent 24 h blood pressure and natriuresis monitoring. Before and after each medication thoracic fluid index and plasma renin, aldosterone and ANP were also assessed. The blood pressure load in the daytime and nighttime were significantly increased after liraglutide compared to placebo in patients with eGFR < 30 ml/min/1.73 m2. In patients with eGFR > 60 ml/min/1.73 m2 the changes of arterial pressure were comparable, while the morning surge was significantly reduced after liraglutide compared to placebo. After liraglutide 24 h urine sodium excretion increased in both groups vs. placebo (p < 0.001), the effect was greatest in subjects with eGFR > 60 ml/min/1.73 m2. Plasma ANP increased after liraglutide in both groups, most in patients with eGFR < 30 ml/min/1.73 m2 group. Plasma aldosterone (p = 0.013) and thoracic fluid index (p = 0.01) decreased after liraglutide compared to placebo (p = 0.013 and p + 0.01, respectively. Plasma renin concentration remained unchanged. In severe chronic kidney disease liraglutide induces a transient increase of blood pressure due to reduced natriuresis. The natriuretic effect of liraglutide in DKD may be related to increased ANP and decreased aldosterone secretion.

Effects of Liraglutide, Empagliflozin and Their Combination on Left Atrial Strain and Arterial Function

Background and Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose cotransporter-2 inhibitors (SGLT-2i) are cardioprotective drugs. We investigated their effects on left atrial function, a major determinant of cardiac diastolic dysfunction in type 2 diabetes mellitus. We also explored the association of changes in arterial stiffness with those of the LA strain after treatment. Materials and Methods: A total of 200 patients (59.5 ± 9.1 year old, 151 male) with type 2 diabetes mellitus treated with metformin were randomized to insulin (n = 50 served as controls), liraglutide (n = 50), empagliflozin (n = 50) or their combination (liraglutide + empagliflozin) (n = 50). We measured at baseline and 6 months post-treatment: (a) left atrial and global left ventricular longitudinal strain by speckle tracking echocardiography; (b) pulse wave velocity (PWV) and central systolic blood pressure. Results: At baseline, there was a correlation of the LA reservoir strain with PWV (r = -0.209, p = 0.008), central SBP (r = -0.151, p = 0.030), EF (r = 0.214, p = 0.004) and GLS (r = -0.279, p = 0.009). The LA reservoir change 6 months post-treatment was correlated with the PWV change in all groups (r = -0.242, p = 0.028). The LA reservoir change 6 months post-treatment was correlated with the GLS change in all groups (r = -0.322, p = 0.004). Six months after intervention, patients treated with liraglutide, empagliflozin and their combination improved the left atrial reservoir strain (GLP1RA 30.7 ± 9.3 vs. 33.9 ± 9.7%, p = 0.011, SGLT2i 30 ± 8.3 vs. 32.3 ± 7.3%, p = 0.04, GLP1&SGLT2i 29.1 ± 8.7 vs. 31.3 ± 8.2, p = 0.007) compared to those treated with insulin (33 ± 8.3% vs. 32.8 ± 7.4, p = 0.829). Also, patients treated with liraglutide and the combination liraglutide and empagliflozin had improved left atrial conduction strain (p < 0.05). Empagliflozin or the combination liraglutide and empagliflozin showed a greater decrease of PWV and central and brachial systolic blood pressure than insulin or GLP-1RA. (p < 0.05). Conclusions: Impaired aortic elastic properties are associated with a decreased LA strain in type 2 diabetics. Treatment with liraglutide, empagliflozin and their combination for 6 months showed a greater improvement of left atrial function compared to insulin treatment in parallel with the improvement of arterial and myocardial functions.

Liraglutide improves sevoflurane-induced postoperative cognitive dysfunction via activating autophagy and inhibiting apoptosis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in elderly patients. Liraglutide (LRG) has high homology (97%) with natural glucagon like peptide-1, and it has been proved to be effective in some nervous system diseases. Whether LRG could regulate POCD has not been reported.

METHODS

Sevoflurane (Sev) was used to simulate postoperative cognitive dysfunction (POCD) model. Morris water maze test was performed to evaluate the memory ability and neurological function of rats. Escape latency, swim distance, crossing platform times, average velocity, and targeting quadrant time were analyzed. The cell apoptosis, mRNA and protein expression were measured through flow cytometry, PCR, and western blotting, respectively.

RESULTS

LRG significantly improved the memory ability and neurological function of Sev-treated rats, but 3-MA reversed the effects of LRG. LRG remarkably inhibited apoptosis but up-regulated autophagy related proteins both in vivo and in vitro levels. However, knocking down AMPK could markedly reverse the influence of LRG on apoptosis, autophagy, and cell apoptosis.

CONCLUSIONS

LRG induced autophagy activation can maintain cell homeostasis and promote cell survival by blocking the apoptotic pathway. LRG could improve Sev-induced POCD via activating autophagy, inhibiting apoptosis, and regulating AMPK/mTOR signaling pathway. This study provides a novel therapeutic strategy for the prevention and treatment of POCD.

Uncovering the potential molecular mechanism of liraglutide to alleviate the effects of high glucose on myoblasts based on high-throughput transcriptome sequencing technique

BACKGROUND

Myoblasts play an important role in muscle growth and repair, but the high glucose environment severely affects their function. The purpose of this study is to explore the potential molecular mechanism of liraglutide in alleviating the effects of high glucose environments on myoblasts.

METHODS

MTT, western blot, and ELISA methods were used to investigate the role of liraglutide on C2C12 myoblasts induced by high glucose. The high-throughput transcriptome sequencing technique was used to sequence C2C12 myoblasts from different treated groups. The DESeq2 package was used to identify differentially expressed-mRNAs (DE-mRNAs). Then, functional annotations and alternative splicing (AS) were performed. The Cytoscape-CytoHubba plug-in was used to identify multicentric DE-mRNAs.

RESULTS

The MTT assay results showed that liraglutide can alleviate the decrease of myoblasts viability caused by high glucose. Western blot and ELISA tests showed that liraglutide can promote the expression of AMPKα and inhibit the expression of MAFbx, MuRF1 and 3-MH in myoblasts. A total of 15 multicentric DE-mRNAs were identified based on the Cytoscape-CytoHubba plug-in. Among them, Top2a had A3SS type AS. Functional annotation identifies multiple signaling pathways such as metabolic pathways, cytokine-cytokine receptor interaction, cAMP signaling pathway and cell cycle.

CONCLUSION

Liraglutide can alleviate the decrease of cell viability and degradation of muscle protein caused by high glucose, and improves cell metabolism and mitochondrial activity. The molecular mechanism of liraglutide to alleviate the effect of high glucose on myoblasts is complex. This study provides a theoretical basis for the clinical effectiveness of liraglutide in the treatment of skeletal muscle lesions in diabetes.

Liraglutide modulates morpho-functional and inflammatory gastrointestinal responses in rats

BACKGROUND

Obesity impairs homeostatic control of energy and is associated with chronic low-grade inflammation. Effects of glucagon-like peptide-1, the target in the gastrointestinal tract for anti-obesity drugs such as Liraglutide, were not properly associated with inflammation markers. This study investigated the effects of Liraglutide on metabolic and gastrointestinal parameters in a rat model of obesity.

METHODS

Twenty-six Wistar rats with obesity were randomly distributed to receive saline (n = 10), 400 μg (n = 8), or 1200 μg of Liraglutide/kg/day (n = 8), subcutaneously for 30 consecutive days, once a day. Weight gain, feeding efficiency, caloric consumption, gastric motility, adiposity, histomorphometric, murinometric, biochemical parameters and cytokines TNF-α and TGF-β1 in duodenal tissue were measured. Data were analysed by ANOVA, followed by Bonferroni post hoc or Kruskal-Wallis test, followed by Dunn's multiple comparison test.

RESULTS

Liraglutide-treated animals had better feeding efficiency and higher caloric intake in a dose-dependent manner. Higher doses slowed gastric emptying and diminished the amplitude of gastric contractions. These effects were accompanied by decreases in intestinal muscle layer thickness and crypt depth. Liraglutide significantly reduced retroperitoneal and visceral white adipose tissue depots. High-dose treatment decreased levels of TNF-α and enhanced levels of TGF-β1 in duodenal tissue. Liraglutide treatment provided significant reductions in total cholesterol, triglyceride and hepatic transaminases.

CONCLUSIONS

Liraglutide reduced fat accumulation, improved metabolic parameters and downregulated levels of inflammatory signalling in duodenal tissue. Liraglutide at high doses controlled obesity-related outcomes, and such effects seemed to be driven by its action on glucagon-like peptide-1 receptors in the gastrointestinal tract slowing gastric motility.

Seladelpar combined with complementary therapies improves fibrosis, inflammation, and liver injury in a mouse model of nonalcoholic steatohepatitis

Seladelpar, a selective peroxisome proliferator-activated receptor δ (PPARδ) agonist, improves markers of hepatic injury in human liver diseases, but histological improvement of nonalcoholic steatohepatitis (NASH) and liver fibrosis has been challenging with any single agent. To discover how complementary agents could work with seladelpar to achieve optimal outcomes, this study evaluated a variety of therapeutics (alone and in combination) in a mouse model of NASH. Mice on a high-fat amylin liver NASH (AMLN) diet were treated for 12 wk with seladelpar, GLP-1-R (glucagon-like peptide-1 receptor) agonist liraglutide, apoptosis signal-regulating kinase 1 (ASK1) inhibitor selonsertib, farnesoid X receptor (FXR) agonist obeticholic acid, and with seladelpar in combination with liraglutide or selonsertib. Seladelpar treatment markedly improved plasma markers of liver function. Seladelpar alone or in combination resulted in stark reductions in liver fibrosis (hydroxyproline, new collagen synthesis rate, mRNA indices of fibrosis, and fibrosis staining) compared with vehicle and the other single agents. Robust reductions in liver steatosis were also observed. Seladelpar produced a reorganization of metabolic gene expression, particularly for those genes promoting peroxisomal and mitochondrial lipid oxidation. In summary, substantial improvements in NASH and NASH-induced fibrosis were observed with seladelpar alone and in combination with liraglutide in this model. Broad gene expression analysis suggests seladelpar should be effective in concert with diverse mechanisms of action.NEW & NOTEWORTHY NASH is a chronic, progressive, and increasingly problematic liver disease that has been resistant to treatment with individual therapeutics. In this study using a diet-induced mouse model of NASH, we found that the PPARδ agonist seladelpar reduced fibrosis and NASH pathology alone and in combinations with a GLP-1-R agonist (liraglutide) or an ASK1 inhibitor (selonsertib). Liver transcriptome analysis comparing each agent and coadministration suggests seladelpar should be effective in combination with a variety of therapeutics.

GLP-1RAs inhibit the activation of the NLRP3 inflammasome signaling pathway to regulate mouse renal podocyte pyroptosis

OBJECTIVE

Podocytes are closely related to renal function as an important part of the glomerulus. The reduction and damage of podocytes lead to further decline of renal function and aggravate the progression of DKD. Glucagon-like peptide-1 receptor agonists (GLP-1RAS) have recently attracted great attention in improving podocyte dysfunction, but the specific mechanism remains uncertain.

METHODS

We used mouse kidney podocyte MPC5 to construct a high-glucose injury model. Cell viability was detected by the MTT method; RT-qPCR and western blotting were used to detect the expressions of NF-κB p65, NLRP3, GSDMD, N-GSDMD, caspase-1 and cleaved-caspase-1, and we used ELISA to detect the expressions of inflammatory factors IL-1β and IL-18.

RESULTS

Our results showed that high glucose decreased podocyte survival, while liraglutide and semaglutide increased podocyte survival under high glucose. Liraglutide and semaglutide can inhibit the expression of pyroptosis-related genes and proteins and also inhibit the expression of inflammatory factors IL-1β, IL-18 increase.

CONCLUSION

The protective effect of liraglutide and semaglutide on podocytes may be achieved by regulating the NLRP3 inflammasome pathway and inhibiting pyroptosis, and there were no significant differences between the two GLP-1RAs (liraglutide and semaglutide) in inhibiting podocyte pyroptosis.

Narrative Review of Effects of Glucagon-Like Peptide-1 Receptor Agonists on Bone Health in People Living with Obesity

Glucagon-like peptide-1 Receptor agonists (GLP-1Ras) such as liraglutide and semaglutide have been recently approved as medications for chronic weight management in people living with obesity (PwO); GLP-1 may enhance bone metabolism and improve bone quality. However, the effects of GLP-1Ras on skeletal health remain to be determined and that's the purpose of this narrative review. Nevertheless, bone consequences of intentional weight loss interventions in PwO are well known: (i) significant weight loss induced by caloric restriction and bariatric surgery results in accelerated bone turnover and bone loss, and (ii) unlike caloric restriction interventions, PwO experience a substantial deterioration in bone microarchitecture and strength associated with an increased risk of fracture after bariatric surgery especially malabsorptive procedures. Liraglutide seems to have a positive effect on bone material properties despite significant weight loss in several rodent models. However, most of positive effects on bone mineral density and microarchitecture were observed at concentration much higher than approved for obesity care in humans. No data have been reported in preclinical models with semaglutide. The current evidence of the effects of GLP-1Ra on bone health in PwO is limited. Indeed, studies on the use of GLP-1Ra mostly included patients with diabetes who were administered a dose used in this condition, did not have adequate bone parameters as primary endpoints, and had short follow-up periods. Further studies are needed to investigate the bone impact of GLP-1Ra, dual- and triple-receptor agonists for GLP-1, glucose-dependent insulin releasing polypeptide (GIP), and glucagon in PwO.

Effects of liraglutide on intrapancreatic fat deposition in patients with type 2 diabetes

BACKGROUND & AIMS

Ectopic fat deposition is associated with worsening of glycemic control. This study was conducted to determine whether liraglutide reduces ectopic fat deposition, especially in pancreas, in patients with type 2 diabetes (T2D).

METHODS

We retrospectively recruited T2D patients who underwent abdominal unenhanced CT scans both before and after administration of liraglutide (N = 13) or glimepiride (N = 29). Using CT values of pancreas (P), liver (L) and spleen (S), we defined the indices of intrapancreatic and liver fat as P-S value and L-S value, respectively. Increase of each value suggests the reduction of each fat deposition.

RESULTS

The values of HbA1c (p = 0.0017) and body weight (p = 0.0081) decreased, and L-S (p = 0.0024) increased significantly after administration of liraglutide compared with those at baseline. Similarly, P-S tended to increase in the liraglutide group (p = 0.0547) and increased significantly in the liraglutide subgroup with fatty pancreas (p = 0.0303), defined as having baseline P-S less than -5. In the glimepiride group, P-S did not increase regardless of baseline P-S. Among patients with fatty pancreas, administration of liraglutide tended to be a significant factor for the change in P-S after adjustment for the change in HbA1c (p = 0.1090) and the change in visceral fat area (p = 0.1030).

CONCLUSIONS

Intrapancreatic fat deposition was decreased after treatment with liraglutide, but not glimepiride, in T2D patients with fatty pancreas. Liraglutide might reduce intrapancreatic fat deposition independently of decreases in HbA1c and visceral fat volume.

Leptin Reduction as a Required Component for Weight Loss

Partial leptin reduction can induce significant weight loss, while weight loss contributes to partial leptin reduction. The cause-and-effect relationship between leptin reduction and weight loss remains to be further elucidated. Here, we show that FGF21 and the glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide rapidly induced a reduction in leptin. This leptin reduction contributed to the beneficial effects of GLP-1R agonism in metabolic health, as transgenically maintaining leptin levels during treatment partially curtailed the beneficial effects seen with these agonists. Moreover, a higher degree of leptin reduction during treatment, induced by including a leptin neutralizing antibody with either FGF21 or liraglutide, synergistically induced greater weight loss and better glucose tolerance in diet-induced obese mice. Furthermore, upon cessation of either liraglutide or FGF21 treatment, the expected immediate weight regain was observed, associated with a rapid increase in circulating leptin levels. Prevention of this leptin surge with leptin neutralizing antibodies slowed down weight gain and preserved better glucose tolerance. Mechanistically, a significant reduction in leptin induced a higher degree of leptin sensitivity in hypothalamic neurons. Our observations support a model that postulates that a reduction of leptin levels is a necessary prerequisite for substantial weight loss, and partial leptin reduction is a viable strategy to treat obesity and its associated insulin resistance.

ARTICLE HIGHLIGHTS

The effect of metformin combined with liraglutide on gut microbiota of Chinese patients with type 2 diabetes

BACKGROUND

Metformin (MET) is a first-line therapy for type-2 diabetes mellitus (T2DM). Liraglutide (LRG) is a glucagon-like peptide-1 receptor agonist used as a second-line therapy in combination with MET.

METHODS

We performed a longitudinal analysis comparing the gut microbiota of overweight and/or pre-diabetic participants (NCP group) with that of each following their progression to T2DM diagnosis (UNT group) using 16S ribosomal RNA gene sequencing of fecal bacteria samples. We also examined the effects of MET (MET group) and MET plus LRG (MET+LRG group) on the gut microbiota of these participants following 60 days of anti-diabetic drug therapy in two parallel treatment arms.

RESULTS

In the UNT group, the relative abundances of Paraprevotella (P = 0.002) and Megamonas (P = 0.029) were greater, and that of Lachnospira (P = 0.003) was lower, compared with the NCP group. In the MET group, the relative abundance of Bacteroides (P = 0.039) was greater, and those of Paraprevotella (P = 0.018), Blautia (P = 0.001), and Faecalibacterium (P = 0.005) were lower, compared with the UNT group. In the MET+LRG group, the relative abundances of Blautia (P = 0.005) and Dialister (P = 0.045) were significantly lower than in the UNT group. The relative abundance of Megasphaera in the MET group was significantly greater than in the MET+LRG group (P = 0.041).

CONCLUSIONS

Treatment with MET and MET+LRG results in significant alterations in gut microbiota, compared with the profiles of patients at the time of T2DM diagnosis. These alterations differed significantly between the MET and MET+LRG groups, which suggests that LRG exerted an additive effect on the composition of gut microbiota.

Glucagon-Like Peptide 1 (GLP-1) Receptor Variants and Glycemic Response to Liraglutide: A Pharmacogenetics Study in Iranian People with Type 2 Diabetes Mellitus

INTRODUCTION

Pharmacogenetics studies suggest that genetic variants have a possible influence on the inter-individual differences in therapeutic response to glucagon-like peptide 1 receptor agonists (GLP-1 RAs). We aimed to examine the potential role of genetic variability of glucagon-like peptide 1 receptor (GLP-1R) on glycemic response to GLP-1 RAs in a population of Iranian people with type 2 diabetes mellitus (T2DM).

METHODS

In this study, we analyzed the data from participants in a non-inferiority randomized clinical trial between 2019 and 2020. Patients received liraglutide 1.8 mg/day subcutaneously for 24 weeks. They were stratified by the baseline hemoglobin A1c (HbA1c) into four categories: 7-7.99, 8-8.99, 9-9.99, and ≥ 10%. In each category, subjects with HbA1c reduction greater than the median ΔHbA1c value for that group were defined as optimal responders. The pooled number of optimal/suboptimal responders in the four groups was used for the comparison. We evaluated two genetic variants of GLP-1R, rs6923761 and rs10305420, using Sanger sequencing. Logistic regression analyses were performed to examine the associations of the GLP-1R variants with the glycemic response in different genetic models.

RESULTS

Out of 233 participants, 120 individuals were optimal responders. Median HbA1c reduction was - 2.5% in the optimal responder group compared with - 1.0% in the suboptimal responder group (P < 0.001). In genetic models, rs10305420 T allele homozygosity was associated with optimal glycemic response to liraglutide compared with heterozygous and wild-type homozygous states (recessive model: OR 3.28, 95% CI 1.41-7.65, P = 0.006; codominant model: OR 2.52, 95% CI 1.03-6.13, P = 0.04). No significant association was found between rs6923761 variant and HbA1c reduction.

CONCLUSION

GLP-1R rs10305420 polymorphism can explain some of the inter-individual differences in glycemic response to liraglutide in a population of Iranian people with T2DM.

Efficacy of High-dose Liraglutide 3.0 mg in Patients with Poor Response to Bariatric Surgery: Real-world Experience and Updated Meta-analysis

PURPOSE

Poor response to bariatric surgery, characterized by insufficient weight loss (IWL) or weight regain (WR), poses a significant challenge in obesity treatment. This study aims to assess the effectiveness of liraglutide in addressing this issue.

MATERIALS AND METHODS

A retrospective, multicenter cohort study investigated the impact of liraglutide 3 mg on weight loss in adults with suboptimal responses or weight regain after bariatric surgery (BS). Additionally, a systematic review and meta-analysis were conducted for a comprehensive evaluation.

RESULTS

A total of 119 patients (mean age 41.03 ± 11.2 years, 71.4% female) who experienced IWL or WR after BS received pharmacologic therapy with liraglutide 3 mg. Mean percent weight loss in the entire cohort was 5.6 ± 2.6% at 12 weeks and 9.3 ± 3.6% at 24 weeks with a significant reduction in waist circumference (p < 0.0001). No serious side effects were reported. A meta-analysis, utilizing the fixed effect model with the metafor package in R, included 6 and 5 papers for the change in body weight and BMI after liraglutide treatment, respectively. The analysis demonstrated a considerable reduction in body weight (7.9; CI - 10.4; - 5.4, p < 0.0001) and BMI (3.09; CI 3.89; - 2.28, p < 0.0001).

CONCLUSION

Liraglutide 3 mg emerges as a viable option for significant weight loss in patients experiencing IWL or WR after BS. Its inclusion in a multimodal, sequential obesity treatment approach proves promising.

Unlocking the miRNA-34a-5p/TGF-β and HMGB1/PI3K/Akt/mTOR crosstalk participate in the enhanced cardiac protection of liraglutide against isoproterenol-induced acute myocardial injury rat model

Liraglutide (LIRA), a drug used to treat type 2 diabetes mellitus that belongs to the glucagon-like peptide-1 class, has recently drawn attention for its potential cardioprotective properties because of its anti-oxidative and anti-inflammatory properties. This current investigation was designed to assess the impact of LIRA on myocardial injury induced by isoproterenol (ISO). The experiment included 24 male Wistar rats in total, and they were divided into four groups: Control, LIRA (200 µg/kg/12 hrs., S.C.), ISO (85 mg/kg, S.C.), and ISO + LIRA. To assess the results, various biochemical and histopathological analyses were carried out. The findings showed elevated serum enzyme levels, a sign of cardiac injury. ISO-treated rats showed an upregulation of oxidative stress and inflammatory biomarkers like MDA, MPO, nitrites, NADPH oxidase, TNF-α, IL-1β, IL-6, 8-Hydroxyguanosine (8-OHdG), and TGF-β, as well as altered gene expressions like TLR-1 and miRNA-34a-5p. According to western blotting analysis, protein levels of AKT, PI3K, and mTOR were obviously enhanced. Additionally, ISO-treated samples showed altered tissue morphology, elevated caspase 3, and decreased Bcl2 concentrations. The levels of these dysregulated parameters were significantly normalized by LIRA therapy, demonstrating its cardioprotective function against ISO-induced myocardial injury in rats. This protective mechanism was linked to anti-inflammatory properties, redox balance restoration, and modulation of the miRNA-34a-5p/TGF-β pathway.

The Key Role of Liraglutide in Preventing Autophagy of Vascular Smooth Muscle Cells in High Glucose Conditions

Background

The glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide (LIRA) is a potential hypoglycemic drug with anti-atherosclerosis (AS) effects. Autophagy in the vascular smooth muscle cells (VSMCs) facilitates AS. However, the role of autophagy in the anti-AS mechanism of LIRA remains unclear.

Aims

To examine the role and mechanisms of autophagy in LIRA’s improvement of the biological characteristics of VSMCs in high glucose conditions.

Study Design

Experimental animal study.

Methods

VSMCs isolated from the thoracic aorta of male SD rats were subjected to a high glucose (HG) condition (25 mM) in Dulbecco’s Modified Eagle’s Medium with or without LIRA, the GLP-1 receptor antagonist exendin9-39 (Exe9-39), a phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002), and autophagy inhibitors (3-methyladenine [3-MA] and bafilomycin A1 [Baf A1]). Acridine orange staining, western blotting, transmission electron microscopy, and mCherry-GFP-LC3 transfection were performed to evaluate the autophagy flux. Additionally, VSMC migration, calcification, proliferation, and apoptosis in HG conditions were observed.

Results

Addition of LIRA alone or in combination with autophagy inhibitors significantly downregulated Beclin, increased the LC3-II/LC3-I ratio, and upregulated p62 in VSMCs in HG conditions. Furthermore, autophagolysosome formation was markedly curbed after treatment with LIRA and/or autophagy inhibitors. Inhibition of autophagy by LIRA and/or the autophagy inhibitors attenuated VSMC phenotype conversion, proliferation, migration, and calcification and promoted VSMC apoptosis in HG conditions. This protective role of LIRA was augmented by LY294002, but inhibited by Exe9-39.

Conclusion

LIRA plays a significant role in the improvement of the biological features of VSMCs in HG conditions.

Liraglutide 3.0 mg (Saxenda©) for Weight Loss and Remission of Pre-Diabetes. Real-World Clinical Evaluation of Effectiveness among Patients Awaiting Bariatric Surgery

OBJECTIVE

The effectiveness of liraglutide 3.0 mg (Saxenda) therapy to induce weight loss among obese patients prior to bariatric surgery remains uncertain.

METHODS

Clinical data was retrospectively obtained from patients with prediabetes (HbA1c 42-47 mmol/mol) and selected patients on the waiting list for bariatric surgery at the Royal Derby Hospital. Clinical data was collected retrospectively at 6, 12, 26 and 52 week intervals. The outcomes included mean weight change, proportion of patients achieving ≥ 5% and ≥ 10% weight loss and achieving HbA1c reduction to normal range values.

RESULTS

Fifty patients (mean age of 46.2 ± 10.5 years; 76% female and 94% had Class III obesity) who completed 52 and/or 26 weeks of treatment were included. Liraglutide 3.0 mg produced a consistent and statistically significant reduction in weight (kg), BMI (kg/m2) and HbA1c (mmol/mol) across all four time intervals. Average ± SD reduction for weight, BMI and HbA1c respectively at 26 weeks were: -10.9 ± 9.1 (P < 0.01), -3.67 ± 3.5 (P < 0.01), -4.7 IQR 4.95 (P < 0.001), and at 52 weeks were: -14 ± 9.2 kg (P < 0.001), -4.64 ± 4.0 (P < 0.001 and -5.5 IQR 4 (P = 0.009). 85.7% and 33.3% of patients achieved ≥ 5% and 10% weight loss target respectively at 52 weeks. 92.3% and 72.2% achieved remission of pre-diabetes by 6 and 12 months respectively. Liraglutide 3.0 mg was well-tolerated with only 10% discontinuing medication due to tolerability issues.

CONCLUSION

Liraglutide 3.0 mg, with lifestyle management, reduced weight and improved glycaemic control. These results support liraglutide's application in certain high-risk populations, including patients waiting for bariatric surgical intervention.

Glucagon-like peptide-1 receptor signaling modifies the extent of diabetic kidney disease through dampening the receptor for advanced glycation end products-induced inflammation

Glucagon like peptide-1 (GLP-1) is a hormone produced and released by cells of the gastrointestinal tract following meal ingestion. GLP-1 receptor agonists (GLP-1RA) exhibit kidney-protective actions through poorly understood mechanisms. Here we interrogated whether the receptor for advanced glycation end products (RAGE) plays a role in mediating the actions of GLP-1 on inflammation and diabetic kidney disease. Mice with deletion of the GLP-1 receptor displayed an abnormal kidney phenotype that was accelerated by diabetes and improved with co-deletion of RAGE in vivo. Activation of the GLP-1 receptor pathway with liraglutide, an anti-diabetic treatment, downregulated kidney RAGE, reduced the expansion of bone marrow myeloid progenitors, promoted M2-like macrophage polarization and lessened markers of kidney damage in diabetic mice. Single cell transcriptomics revealed that liraglutide induced distinct transcriptional changes in kidney endothelial, proximal tubular, podocyte and macrophage cells, which were dominated by pathways involved in nutrient transport and utilization, redox sensing and the resolution of inflammation. The kidney-protective action of liraglutide was corroborated in a non-diabetic model of chronic kidney disease, the subtotal nephrectomised rat. Thus, our findings identify a novel glucose-independent kidney-protective action of GLP-1-based therapies in diabetic kidney disease and provide a valuable resource for exploring the cell-specific kidney transcriptional response ensuing from pharmacological GLP-1R agonism.

Protecting cardiomyocytes from hypoxia-reoxygenation injury, empaglifozin and liraglutide alone or in combination?

OBJECTIVES

Empagliflozin, a sodium-dependent glucose co-transporter 2 (SGLT2) inhibitor, and liraglutide, a GLP-1 receptor (GLP-1R) agonist, are commonly recognized for their cardiovascular benefits in individuals with type 2 diabetes (T2D). In prior studies, we have demonstrated that both drugs, alone or in combination, were able to protect cardiomyocytes from injury induced by diabetes. Mechanistic investigations also suggested that the cardioprotective effect may be independent of diabetes In this study, we utilized a hypoxia-reoxygenation (H/R) model to investigate the cardiovascular benefits of SGLT2 inhibitor empagliflozin and GLP-1 receptor (GLP-1R) agonist liraglutide, both alone and in combination, in the absence of T2D. Our hypothesis was that empagliflozin and liraglutide, either individually or in combination, would demonstrate cardioprotective properties against H/R-induced injury, with an additive and/or synergistic effect anticipated from combination therapy.

METHODS

In this study, the cardiac muscle cell line, HL-1 cells, were treated with vehicle, empagliflozin, liraglutide, or a combination of the two drugs. The cells were then subjected to a hypoxia-reoxygenation (H/R) protocol, consisting of 1 h of hypoxia followed by 24 h of reoxygenation. The effects of the treatments on cytotoxicity, oxidative stress, endothelial nitric oxide synthase (eNOS) activity, phospho-protein kinase C (PKC) beta and phospho-eNOS (Thr495) expression were subsequently evaluated at the end of the treatments.

RESULTS

We found that H/R increased cytotoxicity and reduces eNOS activity, empagliflozin, liraglutide or combination treatment attenuated some or all of these effects with the combination therapy showing the greatest improvement.

CONCLUSIONS

Empagliflozin, liraglutide or combination of these two have cardioprotective effect regardless of diabetes. Cardioprotective effects of SGLT2 inhibitor and GLP-1R agonist is additive and synergistic.

Liraglutide attenuates palmitate-induced apoptosis via PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells

Liraglutide (LRG), one agonist of glucagon-like peptide-1 receptor (GLP1R), has multiple lipid-lowering effects in type 2 diabetes mellitus, however, studies on the role of LRG in saturated fatty acid-induced bone loss are limited. Therefore, our aim was to investigate whether LRG reduces palmitate (PA)-induced apoptosis and whether the mechanism involves PKA/β-catenin/Bcl-2/Bax in osteoblastic MC3T3-E1 cells. MC3T3-E1 cells were treated with different concentrations of PA, LRG, or pretreated with Exendin 9-39 and H89, cell viability, intracellular reactive oxygen species (ROS), cAMP levels, apoptosis and the expression of protein kinase A (PKA) and phosphorylation of PKA (p-PKA), β-catenin and phosphorylation of β-catenin (Ser675)(p-β-catenin), GLP1R, cleaved-capase 3, Bcl2-Associated X Protein (Bax) and B-cell lymphoma-2 (Bcl-2) along with expression of Osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) were evaluated. PA treatment inhibited cell proliferation and cAMP levels, elevated intracellular ROS levels and promoted apoptosis, increased protein expressions of RANKL, Bax and cleaved-caspase3, meanwhile decreased protein expression of OPG and Bcl-2 in a dose-dependent manner. LRG inverted PA-induced apoptosis, increased cAMP levels, promoted expression of p-PKA, p-β-catenin (Ser675) and reversed these gene expressions via increasing GLP1R expression. Pretreatment of the cells with Exendin 9-39 and H89 partially eradicated the protective effect of LRG on PA-induced apoptosis and gene expressions. Therefore, these findings indicated that LRG attenuates PA-induced apoptosis possibly by GLP1R-mediated PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells. Our results point to LRG as a new strategy to attenuate bone loss associated with high fat diet beyond its lipid-lowering actions. LRG inhibits PA-mediated apoptosis via GLP1R-mediated PKA/β-catenin/Bcl-2/ Bax pathway, while possibly enhances PA-inhibited differentiation by regulating the expression of OPG and RANKL.

Weight Loss-Independent Effect of Liraglutide on Insulin Sensitivity in Individuals With Obesity and Prediabetes

Metabolic effects of glucagon-like peptide 1 (GLP-1) receptor agonists are confounded by weight loss and not fully recapitulated by increasing endogenous GLP-1. We tested the hypothesis that GLP-1 receptor (GLP-1R) agonists exert weight loss-independent, GLP-1R-dependent effects that differ from effects of increasing endogenous GLP-1. Individuals with obesity and prediabetes were randomized to receive for 14 weeks the GLP-1R agonist liraglutide, a hypocaloric diet, or the dipeptidyl peptidase 4 (DPP-4) inhibitor sitagliptin. The GLP-1R antagonist exendin(9-39) and placebo were administered in a two-by-two crossover study during mixed-meal tests. Liraglutide and diet, but not sitagliptin, caused weight loss. Liraglutide improved insulin sensitivity measured by HOMA for insulin resistance (HOMA-IR), the updated HOMA model (HOMA2), and the Matsuda index after 2 weeks, prior to weight loss. Liraglutide decreased fasting and postprandial glucose levels, and decreased insulin, C-peptide, and fasting glucagon levels. In contrast, diet-induced weight loss improved insulin sensitivity by HOMA-IR and HOMA2, but not the Matsuda index, and did not decrease glucose levels. Sitagliptin increased endogenous GLP-1 and GIP values without altering insulin sensitivity or fasting glucose levels, but decreased postprandial glucose and glucagon levels. Notably, sitagliptin increased GIP without altering weight. Acute GLP-1R antagonism increased glucose levels in all groups, increased the Matsuda index and fasting glucagon level during liraglutide treatment, and increased endogenous GLP-1 values during liraglutide and sitagliptin treatments. Thus, liraglutide exerts rapid, weight loss-independent, GLP-1R-dependent effects on insulin sensitivity that are not achieved by increasing endogenous GLP-1.

ARTICLE HIGHLIGHTS

Metabolic benefits of glucagon-like peptide 1 (GLP-1) receptor agonists are confounded by weight loss and are not fully achieved by increasing endogenous GLP-1 through dipeptidyl peptidase 4 (DPP-4) inhibition. We investigated weight loss-independent, GLP-1 receptor (GLP-1R)-dependent metabolic effects of liraglutide versus a hypocaloric diet or the DPP-4 inhibitor sitagliptin. GLP-1R antagonism with exendin(9-39) was used to assess GLP-1R-dependent effects during mixed meals. Liraglutide improved insulin sensitivity and decreased fasting and postprandial glucose prior to weight loss, and these benefits were reversed by exendin(9-39). GLP-1R agonists exert rapid, weight loss-independent, GLP-1R-dependent effects on insulin sensitivity not achieved by increasing endogenous GLP-1.

Institutional experience on the impact of glucagon-like peptide-1 agonists (GLP-1) on glycemic control and weight loss in patients with type 2 diabetes at the Dubai Diabetes Center, United Arab Emirates

AIMS

To describe the effect of three classes of GLP1 analogues on HbA1c and weight over one year in a homogenous group of patients at the Dubai Diabetes Center in Dubai, United Arab Emirates. The specific objectives are to study the extent of change in HbA1c and weight loss on these medications as well as the sustainability of change over one year.

METHODS

A retrospective audit of patients diagnosed Type 2 diabetes receiving one of the three following GLP-1 agonists (Exenatide LA 2 mg weekly, liraglutide 1.8 mg once daily, Dulaglutide 1.5 mg) over one year and documenting changes in HbA1c and weight at 3-, 6-, 9-, and 12-months intervals.

RESULTS

The study shows that while there was significant reduction in HbA1c and weight in the first 3 months, this change was not clinically significant. Also, the change was not maintained at the end of the year. By the final quarter, the effect of the medication diminishes, accompanied by a partial regain of weight.

CONCLUSION

GLP1 agonists favorable initial effect on HbA1c and weight may not be sustainable beyond a certain period. The exact reason and factors contributing to this need further exploration.

Glucagon-Like Peptide Receptor Agonist Inhibits Angiotensin II-Induced Proliferation and Migration in Vascular Smooth Muscle Cells and Ameliorates Phosphate-Induced Vascular Smooth Muscle Cells Calcification

BACKGRUOUND

Glucagon-like peptide-1 receptor agonist (GLP-1RA), which is a therapeutic agent for the treatment of type 2 diabetes mellitus, has a beneficial effect on the cardiovascular system.

METHODS

To examine the protective effects of GLP-1RAs on proliferation and migration of vascular smooth muscle cells (VSMCs), A-10 cells exposed to angiotensin II (Ang II) were treated with either exendin-4, liraglutide, or dulaglutide. To examine the effects of GLP-1RAs on vascular calcification, cells exposed to high concentration of inorganic phosphate (Pi) were treated with exendin-4, liraglutide, or dulaglutide.

RESULTS

Ang II increased proliferation and migration of VSMCs, gene expression levels of Ang II receptors AT1 and AT2, proliferation marker of proliferation Ki-67 (Mki-67), proliferating cell nuclear antigen (Pcna), and cyclin D1 (Ccnd1), and the protein expression levels of phospho-extracellular signal-regulated kinase (p-Erk), phospho-c-JUN N-terminal kinase (p-JNK), and phospho-phosphatidylinositol 3-kinase (p-Pi3k). Exendin-4, liraglutide, and dulaglutide significantly decreased the proliferation and migration of VSMCs, the gene expression levels of Pcna, and the protein expression levels of p-Erk and p-JNK in the Ang II-treated VSMCs. Erk inhibitor PD98059 and JNK inhibitor SP600125 decreased the protein expression levels of Pcna and Ccnd1 and proliferation of VSMCs. Inhibition of GLP-1R by siRNA reversed the reduction of the protein expression levels of p-Erk and p-JNK by exendin-4, liraglutide, and dulaglutide in the Ang II-treated VSMCs. Moreover, GLP-1 (9-36) amide also decreased the proliferation and migration of the Ang II-treated VSMCs. In addition, these GLP-1RAs decreased calcium deposition by inhibiting activating transcription factor 4 (Atf4) in Pi-treated VSMCs.

CONCLUSION

These data show that GLP-1RAs ameliorate aberrant proliferation and migration in VSMCs through both GLP-1Rdependent and independent pathways and inhibit Pi-induced vascular calcification.

Effect of Liraglutide on Osteoporosis in a Rat Model of Type 2 Diabetes Mellitus: A Histological, Immunohistochemical, and Biochemical Study

Diabetic osteoporosis (DOP) is a diabetic complication associated with a significant disability rate. Liraglutide, a glucagon-like peptide-1 receptor agonist, is a promising and innovative drug for type 2 diabetes mellitus (T2DM), with potential therapeutic implications for bone disorders. This investigation examined the impact of liraglutide on osteoporosis in rats with T2DM and studied the influence of vitamin D receptor Bsm1 polymorphism on liraglutide-induced outcomes. Thirty rats were divided into control, T2DM induced by a combination of a high-fat diet and 25 mg/kg streptozotocin, and T2DM-liraglutide (T2DM treated with 0.4 mg/kg/day liraglutide) groups. After 8 weeks of liraglutide treatment, femurs and blood samples were obtained from all rats for subsequent investigations. Diabetes induced a remarkable rise in the serum levels of receptor activator of nuclear factor kappa B ligand (RANKL) and C-telopeptide of type I collagen (CTX-1) associated with a remarkable decline in osteocalcin and osteoprotegerin (OPG). Impaired bone architecture was also demonstrated by light and scanning electron microscopic study. The immune expression of OPG was down-regulated, while RANKL was up-regulated. Interestingly, the administration of liraglutide ameliorated the previous changes induced by diabetes mellitus. In conclusion, liraglutide can prevent DOP, mostly due to liraglutide's ability to increase bone growth, while inhibiting bone resorption.

GLP-1 receptor agonist liraglutide inhibits the proliferation and migration of thyroid cancer cells

This research was done to find out how liraglutide affected the growth and movement of two human thyroid cancer cell lines overexpressing GLP-1 receptor (migration of medullary thyroid cancer TT/GLP-1R and papillary thyroid carcinoma TCP-1/GLP-1R). Flow cytometer and cAMP assays were used to identify the expression and activation of GLP-1R in two stable cell lines. Counting Kit-8 for Cells was applied to examine the proliferative ability of cells in two stable cell lines after treatment with different concentrations of liraglutide at indicated time points. To track the capacity for cell migration, the Transwell test was utilized. We found that liralutide-activated GLP-1R could significantly reduce the growth and metastasis of two kinds of thyroid tumor cells, and the inhibitory effect was dose- and time- dependent. The phosphorylatios of Akt, S6K1, and 70SK declined after receiving liraglutide therapy In our previous studies, we found that the GLP-1 receptor agonist Liraglutide inhibited the proliferation and migration of thyroid cancer cells through the PI3K/Akt/mTOR pathway. This finding provides a theoretical basis for the treatment of diabetes mellitus complicated with medullary thyroid cancer, and is relatively safe.

Glucagon-like Peptide-1 Receptor Pathway Attenuates Platelet Activation in Aspirin-Exacerbated Respiratory Disease

Platelets are key contributors to allergic asthma and aspirin-exacerbated respiratory disease (AERD), an asthma phenotype involving platelet activation and IL-33-dependent mast cell activation. Human platelets express the glucagon-like peptide-1 receptor (GLP-1R). GLP-1R agonists decrease lung IL-33 release and airway hyperresponsiveness in mouse asthma models. We hypothesized that GLP-1R agonists reduce platelet activation and downstream platelet-mediated airway inflammation in AERD. GLP-1R expression on murine platelets was assessed using flow cytometry. We tested the effect of the GLP-1R agonist liraglutide on lysine-aspirin (Lys-ASA)-induced changes in airway resistance, and platelet-derived mediator release in a murine AERD model. We conducted a prospective cohort study comparing the effect of pretreatment with liraglutide or vehicle on thromboxane receptor agonist-induced in vitro activation of platelets from patients with AERD and nonasthmatic controls. GLP-1R expression was higher on murine platelets than on leukocytes. A single dose of liraglutide inhibited Lys-ASA-induced increases in airway resistance and decreased markers of platelet activation and recruitment to the lung in AERD-like mice. Liraglutide attenuated thromboxane receptor agonist-induced activation as measured by CXCL7 release in plasma from patients with AERD and CD62P expression in platelets from both patients with AERD (n = 31) and nonasthmatic, healthy controls (n = 11). Liraglutide, a Food and Drug Administration-approved GLP-1R agonist for treatment of type 2 diabetes and obesity, attenuates in vivo platelet activation in an AERD murine model and in vitro activation in human platelets in patients with and without AERD. These data advance the GLP-1R axis as a new target for platelet-mediated inflammation warranting further study in asthma.

The potential protective effect of liraglutide on valproic acid induced liver injury in rats: Targeting HMGB1/RAGE axis and RIPK3/MLKL mediated necroptosis

Valproic acid (VPA) is a commonly used drug for management of epilepsy. Prolonged VPA administration increases the risk of hepatotoxicity. Liraglutide is a glucagon-like peptide 1 receptor (GLP-1R) agonist that act as a novel antidiabetic drug with broad-spectrum anti-inflammatory and antioxidant effects. This study tested the protective effect of liraglutide against VPA-induced hepatotoxicity elucidating the possible underlying molecular mechanisms. Forty adult male rats were allocated in to four equally sized groups; Group I (control group) received oral distilled water and subcutaneous normal saline for 2 weeks followed by subcutaneous normal saline only for 2 weeks. Group II (liraglutide group) received subcutaneous liraglutide dissolved in normal saline daily for 4 weeks. Group III (valproic acid-treated group) received sodium valproate dissolved in distilled water for 2 weeks. Group IV (Combined valproic acid & liraglutide treated group) received valproic acid plus liraglutide daily for 2 weeks which was continued for additional 2 weeks after valproic acid administration. The hepatic index was calculated. Serum AST, ALT, GGT, and ALP activities were estimated. Hepatic tissue homogenate MDA, GSH, SOD, HMGB1, MAPK, RIPK1, and RIPK3 levels were evaluated using ELISA. However, hepatic RAGE and MLKL messenger RNA expression levels using the QRT-PCR technique. Hepatic NF-κB and TNF-α were detected immunohistochemically. Results proved that liraglutide coadministration significantly decreased liver enzymes, MDA, HMGB1, MAPK, RIPK1 RIPK3, RAGE, and MLKL with concomitant increased GSH and SOD in comparison to the correspondent values in VPA-hepatotoxicity group. Conclusions: Liraglutide's protective effects against VPA-induced hepatotoxicity are triggered by ameliorating oxidative stress, inflammation, and necroptosis.

A randomized controlled trial investigating the effect of liraglutide on self-reported liking and neural responses to food stimuli in participants with obesity

BACKGROUND/OBJECTIVES

Obesity is a complex condition and the mechanisms involved in weight gain and loss are not fully understood. Liraglutide, a GLP-1 receptor agonist, has been demonstrated to successfully promote weight loss in patients with obesity (OB). Yet, it is unclear whether the observed weight loss is driven by an alteration of food liking. Here we investigated the effects of liraglutide on food liking and the cerebral correlates of liking in OB.

SUBJECTS/METHODS

This study was a randomized, single-center, double-blind, placebo-controlled, parallel group, prospective clinical trial. 73 participants with OB and without diabetes following a multidisciplinary weight loss program, were randomly assigned (1:1) to receive liraglutide 3.0 mg (37.40 ± 11.18 years old, BMI = 35.89 ± 3.01 kg) or a placebo (40.04 ± 14.10 years old, BMI = 34.88 ± 2.87 kg) subcutaneously once daily for 16 weeks.

INTERVENTIONS/METHODS

We investigated liking during food consumption. Participants reported their hedonic experience while consuming a high-calorie food (milkshake) and a tasteless solution. The solutions were administered inside the scanner with a Magnetic Resonance Imaging (MRI)-compatible gustometer to assess neural responses during consumption. The same procedure was repeated during the pre- and post-intervention sessions.

RESULTS

None of the effects involving the intervention factor reached significance when comparing liking between the pre- and post-intervention sessions or groups. Liking during food reward consumption was associated with the activation of the ventromedial prefrontal cortex (vmPFC) and the amygdala. The liraglutide group lost more weight (BMI post-pre = -3.19 ± 1.28 kg/m2) than the placebo group (BMI post-pre = -0.60 ± 1.26 kg/m2).

CONCLUSIONS

These results suggest that liraglutide leads to weight loss without self-report or neural evidence supporting a concomitant reduction of food liking in participants with OB.

A Spectroscopic and Molecular Dynamics Study on the Aggregation Properties of a Lipopeptide Analogue of Liraglutide, a Therapeutic Peptide against Diabetes Type 2

The pharmacokinetics of peptide drugs are strongly affected by their aggregation properties and the morphology of the nanostructures they form in their native state as well as in their therapeutic formulation. In this contribution, we analyze the aggregation properties of a Liraglutide analogue (LG18), a leading drug against diabetes type 2. LG18 is a lipopeptide characterized by the functionalization of a lysine residue (K26) with an 18C lipid chain. To this end, spectroscopic experiments, dynamic light scattering measurements, and molecular dynamics simulations were carried out, following the evolution of the aggregation process from the small LG18 clusters formed at sub-micromolar concentrations to the mesoscopic aggregates formed by aged micromolar solutions. The critical aggregation concentration of LG18 in water (pH = 8) was found to amount to 4.3 μM, as assessed by the pyrene fluorescence assay. MD simulations showed that the LG18 nanostructures are formed by tetramer building blocks that, at longer times, self-assemble to form micrometric supramolecular architectures.

Mitigation of Hearing Damage With Liraglutide Treatment in Chinchillas After Repeated Blast Exposures at Mild-TBI

INTRODUCTION

Although hearing protection devices (HPDs) have been widely used during training and combat, over one million veterans experience service-connected hearing loss. Hearing damage has been reported to be associated with blast-induced mild traumatic brain injury (mTBI) and there is a lack of understanding and treatment. Liraglutide is a glucagon-like peptide-1 receptor agonist and a potential treatment for TBI-induced memory deficits. This study aims to investigate the function of the liraglutide to prevent damage and facilitate hearing restoration in chinchillas exposed to multiple high-intensity, mTBI-level blasts.

MATERIALS AND METHODS

Chinchillas were divided into three treatment groups: blast control, pre-blast drug treatment, and post-blast drug treatment. On day 1, the chinchilla ears were protected by HPDs and exposed to three blasts with peak pressure levels of 15-25 psi. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) were recorded pre- and post-blast on day 1 and on days 4, 7, 14, and 28.

RESULTS

Substantial acute damage was observed and progressively recovered in chinchillas after the blast exposures. The pre-blast treatment group exhibited the lowest elevation of the ABR threshold and reduction of the wave I amplitude on day 1 after blasts. The liraglutide treatment insignificantly facilitated the recovery of the DPOAE levels and ABR thresholds on days 14 and 28. The pre-blast treatment chinchillas showed reduced MLR amplitudes on days 4 and 7.

CONCLUSIONS

This study indicated that the pre-blast liraglutide administration provided damage protection against blasts in addition to the HPDs. Current evidence suggests that the effect of liraglutide is more prominent in the early phase of the experiment.

Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of Raptor and this contributes to the weight loss effect of liraglutide

The canonical target of the glucagon-like peptide-1 receptor (GLP-1R), Protein Kinase A (PKA), has been shown to stimulate mechanistic Target of Rapamycin Complex 1 (mTORC1) by phosphorylating the mTOR-regulating protein Raptor at Ser791 following β-adrenergic stimulation. The objective of these studies is to test whether GLP-1R agonists similarly stimulate mTORC1 via PKA phosphorylation of Raptor at Ser791 and whether this contributes to the weight loss effect of the therapeutic GLP-1R agonist liraglutide. We measured phosphorylation of the mTORC1 signaling target ribosomal protein S6 in Chinese Hamster Ovary cells expressing GLP-1R (CHO-Glp1r) treated with liraglutide in combination with PKA inhibitors. We also assessed liraglutide-mediated phosphorylation of the PKA substrate RRXS*/T* motif in CHO-Glp1r cells expressing Myc-tagged wild-type (WT) Raptor or a PKA-resistant (Ser791Ala) Raptor mutant. Finally, we measured the body weight response to liraglutide in WT mice and mice with a targeted knock-in of PKA-resistant Ser791Ala Raptor. Liraglutide increased phosphorylation of S6 and the PKA motif in WT Raptor in a PKA-dependent manner but failed to stimulate phosphorylation of the PKA motif in Ser791Ala Raptor in CHO-Glp1r cells. Lean Ser791Ala Raptor knock-in mice were resistant to liraglutide-induced weight loss but not setmelanotide-induced (melanocortin-4 receptor-dependent) weight loss. Diet-induced obese Ser791Ala Raptor knock-in mice were not resistant to liraglutide-induced weight loss; however, there was weight-dependent variation such that there was a tendency for obese Ser791Ala Raptor knock-in mice of lower relative body weight to be resistant to liraglutide-induced weight loss compared to weight-matched controls. Together, these findings suggest that PKA-mediated phosphorylation of Raptor at Ser791 contributes to liraglutide-induced weight loss.

Novel cannabinoid receptor 1 inverse agonist CRB-913 enhances efficacy of tirzepatide, semaglutide, and liraglutidein the diet-induced obesity mouse model

OBJECTIVE

Incretin receptor agonists are now standard of care in treating obesity. Their efficacy and tolerability might be further improved by combining them with compounds that offer orthogonal mechanisms of action. The cannabinoid type 1 receptor (CB1R) is a clinically validated therapeutic target in obesity, and several experimental CB1R inverse agonists have been shown to induce weight loss.

METHODS

This study characterizes a novel CB1R inverse agonist (CRB-913) with similar preclinical potency to rimonabant but markedly reduced brain penetration. CRB-913 was tested as monotherapy and in combination with tirzepatide, semaglutide, or liraglutide in the diet-induced obesity (DIO) mouse model for body weight reduction.

RESULTS

CRB-913 demonstrated enhanced plasma exposure (3.8-fold larger area under the curvelast ) and reduced brain levels (9.5-fold lower area under the curvelast ) than rimonabant. CRB-913 monotherapy yielded a dose-dependent decrease in body weight in DIO mice reaching -22% within 18 days. In further DIO studies in combination with tirzepatide, semaglutide, or liraglutide, CRB-913 (2.5 mg/kg) resulted in -32.6%, -28.8%, and -16.8% decreases in body weight on Day 18, respectively, with concomitant improvements in body fat content, liver triglycerides, and liver fat deposits.

CONCLUSIONS

CRB-913 in combination with incretin analogues could deliver meaningful improvements over current standards of care for obesity and related conditions.

Modulatory effect of liraglutide on doxorubicin-induced testicular toxicity and behavioral abnormalities in rats: role of testicular-brain axis

Doxorubicin (DOX) is a powerful chemotherapeutic agent used in many types of malignancies. However, its use results in testicular damage. DOX-induced testicular damage results in low level of serum testosterone which may affect cognitive function. The current study investigated the protective effect of liraglutide (50, 100 μg/kg/day) in testicular toxicity and the consequent cognitive impairment induced by DOX. DOX treatment reduced sperm count (62%) and sperm motility (53%) and increased sperm abnormalities (786%), as compared to control group. DOX also reduced serum testosterone level (85%) and the gene expression of testicular 3β-HSD (68%) and 17β-HSD (82%). Moreover, it increased testicular oxidative stress (MDA and GSH) by 103% and 59%, respectively, apoptotic (caspase-3 and P53) by 996% and 480%, respectively. In addition, DOX resulted in increasing autophagic markers including PAKT, mTOR, and LC3 by 48%, 56%, and 640%, respectively. Additionally, rats' behavior in Y-maze (60%) and passive avoidance task (85%) was disrupted. The histopathological results of testis and brain supported the biochemical findings. Treatment with liraglutide (100 μg/kg/day) significantly abrogated DOX-induced testicular damage by restoring testicular architecture, increasing sperm count (136%) and sperm motility (106%), and decreasing sperm abnormalities (84%) as compared to DOX group. Furthermore, liraglutide increased serum testosterone (500%) and steroidogenesis enzymes 3β-HSD (105%) and 17β-HSD (181%) along with suppressing oxidative stress (MDA and GSH) by 23% and 85%, respectively; apoptotic (caspase-3 and P53) by 59% and55%, respectively; and autophagic markers including PAKT, mTOR, and LC3 by 48%, 97%, and 60%, respectively. Moreover, it enhanced the memory functions in passive avoidance and Y-maze tests (132%). In conclusion, liraglutide is a putative agent for protection against DOX-induced testicular toxicity and cognitive impairment through its antioxidant, antiapoptotic, and antiautophagic effects.