Liraglutide Increases the Catabolism of Apolipoprotein B100-Containing Lipoproteins in Patients With Type 2 Diabetes and Reduces Proprotein Convertase Subtilisin/Kexin Type 9 Expression

Dapagliflozin modulates hepatic lipid metabolism through the proprotein convertase subtilisin/kexin type 9/low density lipoprotein receptor pathway

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is mainly secreted by the liver, and plays a crucial role in lipid metabolism disorder. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) can regulate lipid metabolism through various pathways, including reducing visceral fat accumulation, modulating serum lipoprotein levels and alleviating hepatic steatosis. However, the specific regulatory mechanisms remain unclear.

METHODS

We built a model of glucose and lipid metabolism disorder in vivo and in vitro, and explored the regulatory mechanism of dapagliflozin in regulating liver lipid metabolism.

RESULTS

We found that the SGLT2i dapagliflozin significantly reduced serum levels of PCSK9, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) in high-fat diet (HFD)-fed mice, while also improving hepatic steatosis. In vitro studies confirmed that dapagliflozin increased LDL receptor (LDLR) expression in HepG2 cells, enhancing their ability to uptake LDL-C.

CONCLUSIONS

Further mechanistic studies revealed that the hepatocyte nuclear factor-1-alpha (HNF1α)/PCSK9/LDLR signalling pathway may be involved in dapagliflozin's regulation of lipid metabolism homeostasis.

Stroke in the Patient With Type 2 Diabetes

OBJECTIVE

Persons living with type 2 diabetes mellitus (T2DM) have a significantly greater risk of stroke (1.5 to 3 times higher than normoglycemic individuals). The traditional approach to primary and secondary stroke prevention has been control of risk factors. While this has resulted in prolongation of life in patients with diabetes, the risk for recurrent stroke in these patients still remains higher than in the normoglycemic population, and patients with T2DM post stroke have a poorer quality of life (increases in handicap and death).

METHODS

Multiple publications on the pathophysiology which increases stroke in T2DM were reviewed as well as new publications looking at the effect of traditional and new risk factor modification on stroke are summarized.

RESULTS

Traditional risk factor modification is refined with recommended levels of lipids and blood pressure and methods of anticoagulation. More recently, studies with antidiabetic drugs (glucagon-like peptide 1 RA and pioglitazone) have been shown to prevent both primary and secondary stroke in patients with diabetes.

CONCLUSIONS

Worldwide, stroke is the second leading cause of death and the third leading cause of disability. Both risk and the outcomes are greatly worsened by the presence of T2DM. Newer recommendations can improve these outcomes.

Clinical study on the effect of jejunoileal side-to-side anastomosis on metabolic parameters in patients with type 2 diabetes

BACKGROUND

At present, the existing internal medicine drug treatment can alleviate the high glucose toxicity of patients to a certain extent, to explore the efficacy of laparoscopic jejunoileal side to side anastomosis in the treatment of type 2 diabetes, the report is as follows.

AIM

To investigate the effect of jejunoileal side-to-side anastomosis on metabolic parameters in patients with type 2 diabetes mellitus (T2DM).

METHODS

We retrospectively analyzed the clinical data of 78 patients with T2DM who were treated via jejunoileal lateral anastomosis. Metabolic indicators were collected preoperatively, as well as at 3 and 6 months postoperative. The metabolic indicators analyzed included body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), 2-hour blood glucose (PBG), glycated hemoglobin (HbA1c), fasting C-peptide, 2-hour C-peptide (PCP), fasting insulin (Fins), 2-hour insulin (Pins), insulin resistance index (HOMA-IR), β Cellular function index (HOMA-β), alanine aminotransferase, aspartate aminotransferase, serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), high-density lipoprotein, and uric acid (UA) levels.

RESULTS

SBP, DBP, PBG, HbA1c, LDL-C, and TG were all significantly lower 3 months postoperative vs preoperative values; body weight, BMI, SBP, DBP, FBG, PBG, HbA1c, TC, TG, UA, and HOMA-IR values were all significantly lower 6 months postoperative vs at 3 months; and PCP, Fins, Pins, and HOMA-β were all significantly higher 6 months postoperative vs at 3 months (all P < 0.05).

CONCLUSION

Side-to-side anastomosis of the jejunum and ileum can effectively treat T2DM and improve the metabolic index levels associated with it.

Glucagon-like peptide 1 receptor agonists modestly reduced low-density lipoprotein cholesterol and total cholesterol levels independent of weight reduction: a meta-analysis and meta-regression of placebo controlled randomized controlled trials

BACKGROUND

The effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on lipid components are unclear. We aim to quantify the lipid lowering effects of GLP1-RAs.

METHODS

A comprehensive database search for placebo-controlled randomized controlled trials (RCTs) on GLP-1RA treatment was conducted until January 2023. Data extraction and quality assessment were performed, and outcomes were analyzed using a random-effects model to calculate weighted mean differences (MDs) in milligrams per deciliter (mg/dl) and 95% confidence intervals (CIs). The primary endpoint was the mean difference in low-density lipoprotein cholesterol (LDL-C). Secondary endpoints included total cholesterol (TC), triglycerides, high density lipoprotein-C (HLD-C), and very low-density lipoprotein-C (VLDL-C). Subgroup analyses and meta-regression accounted for covariates.

RESULTS

GLP-1RAs modestly reduced LDL-C (MD -2.93, 95% CI (-5.01, -0.85), p = 0.01), consistent across treatment durations: ≤12 weeks (MD: -5.39, 95% CI (-10.36, -0.42), p = 0.03) and >12 weeks (MD: -2.39, 95% CI (-4.70, -0.007), p = 0.04). GLP-1RA reduced TC by ∼7 mg/dl. There was no significant reduction in triglycerides (MD = -7.19, 95% CI (-15.01, 0.62), p = 0.07) or VLDL-C (MD = -3.99, 95%, CI (-8.73, 0.75), p = 0.10). GLP-1RA did not increase HDL-C (MD = -0.12, 95% CI (-0.73, 0.49), p = 0.69). Weight change did not influence LDL-C (tau2 = 28.38, I2 = 99.83, R2 = 0.0, p = 0.67) or TC (tau2 = 93.6, I2 = 99.86, R2 = 0.0, p = 0.92).

CONCLUSION

GLP-1RA treatment modestly decreased LDL-C and TC but did not significantly affect triglycerides, VLDL-C, or HDL-C.

Are the lipid-lowering effects of incretin-based therapies relevant for cardiovascular benefit?

PURPOSE OF REVIEW

This review examines the impact of glucagon-like peptide 1 receptor agonists (GLP-1RAs) on lipid profiles in individuals with type 2 diabetes mellitus and/or obesity, crucial for optimizing cardiovascular risk management.

RECENT FINDINGS

GLP-1RAs affect lipid levels by reducing intestinal apolipoprotein B48 production and mesenteric lymph flow, while increasing catabolism of apolipoprotein B100. It remains unknown whether these effects are direct or indirect, but the improvements in lipid levels are strongly correlated to the drug-induced weight loss. Clinical trials demonstrate improvements in lipid profiles, with different effects per agent and dose. We deem it unlikely that improved lipid levels are sufficient to explain the beneficial effects of GLP-1RA on cardiovascular risk, especially given the improvement of many other risk factors (body weight, glycemic control, inflammation) while using these agents. Posthoc mediation analyses of large cardiovascular outcome trials may shed some light on the relative importance of each risk factor.

SUMMARY

GLP-1RAs improve lipid profiles in clinical trials, but their complete cardiovascular benefits likely involve multifactorial mechanisms beyond lipid modulation.

Pharmacologic Treatment of Obesity in adults and its impact on comorbidities: 2024 Update and Position Statement of Specialists from the Brazilian Association for the Study of Obesity and Metabolic Syndrome (Abeso) and the Brazilian Society of Endocrinology and Metabolism (SBEM)

Pharmacological treatment of obesity is passing through many changes in the last decades; different agents have been approved, and newer options are leaning towards higher efficacy and a more favourable safety profile; however, medications approved for a longer time are still available and useful for many patients. This document is an 2024 Update Position Statement of Specialists from the Brazilian Association for the Study of Obesity and Metabolic Syndrome (Abeso) and the Brazilian Society of Endocrinology and Metabolism (SBEM), with the aim of reviewing all the approved medications for the management of obesity in Brazil (sibutramine, orlistat, liraglutide, semaglutide and bupropion/naltrexone fixed dose), with the addition of tirzepatide, that is approved in other countries and likely approved soon in Brazil. The review is focused on efficacy, safety profile and the impact of drugs (based on existing studies) on different comorbidities.

Hypertriglyceridemia Results From an Impaired Catabolism of Triglyceride-Rich Lipoproteins in PLIN1-Related Lipodystrophy

BACKGROUND

Pathogenic variants in PLIN1-encoding PLIN1 (perilipin-1) are responsible for an autosomal dominant form of familial partial lipodystrophy (FPL) associated with severe insulin resistance, hepatic steatosis, and important hypertriglyceridemia. This study aims to decipher the mechanisms of hypertriglyceridemia associated with PLIN1-related FPL.

METHODS

We performed an in vivo lipoprotein kinetic study in 6 affected patients compared with 13 healthy controls and 8 patients with type 2 diabetes. Glucose and lipid parameters, including plasma LPL (lipoprotein lipase) mass, were measured. LPL mRNA and protein expression were evaluated in abdominal subcutaneous adipose tissue from patients with 5 PLIN1-mutated FPL and 3 controls.

RESULTS

Patients with PLIN1-mutated FPL presented with decreased fat mass, insulin resistance, and diabetes (glycated hemoglobin A1c, 6.68±0.70% versus 7.48±1.63% in patients with type 2 diabetes; mean±SD; P=0.27). Their plasma triglycerides were higher (5.96±3.08 mmol/L) than in controls (0.76±0.27 mmol/L; P<0.0001) and patients with type 2 diabetes (2.94±1.46 mmol/L, P=0.006). Compared with controls, patients with PLIN1-related FPL had a significant reduction of the indirect fractional catabolic rate of VLDL (very-low-density lipoprotein)-apoB100 toward IDL (intermediate-density lipoprotein)/LDL (low-density lipoprotein; 1.79±1.38 versus 5.34±2.45 pool/d; P=0.003) and the indirect fractional catabolic rate of IDL-apoB100 toward LDL (2.14±1.44 versus 7.51±4.07 pool/d; P=0.005). VLDL-apoB100 production was not different between patients with PLIN1-related FPL and controls. Compared with patients with type 2 diabetes, patients with PLIN1-related FPL also showed a significant reduction of the catabolism of both VLDL-apoB100 (P=0.031) and IDL-apoB100 (P=0.031). Plasma LPL mass was significantly lower in patients with PLIN1-related FPL than in controls (21.03±10.08 versus 55.76±13.10 ng/mL; P<0.0001), although the LPL protein expression in adipose tissue was similar. VLDL-apoB100 and IDL-apoB100 indirect fractional catabolic rates were negatively correlated with plasma triglycerides and positively correlated with LPL mass.

CONCLUSIONS

We show that hypertriglyceridemia associated with PLIN1-related FPL results from a marked decrease in the catabolism of triglyceride-rich lipoproteins (VLDL and IDL). This could be due to a pronounced reduction in LPL availability, related to the decreased adipose tissue mass.

No effect of liraglutide on high density lipoprotein apolipoprotein AI kinetics in patients with type 2 diabetes

AIM

The catabolism of high density lipoprotein (HDL) apolipoprotein AI (apoAI) is accelerated in patients with type 2 diabetes (T2D), related to hypertriglyceridemia, insulin resistance and low plasma adiponectin levels. Since liraglutide is likely to partly correct these abnormalities, we hypothesized that it might have a beneficial effect on HDL apoAI kinetics in patients with T2D.

METHODS

An in vivo kinetic study of HDL apoAI was performed in 10 patients with T2D before and after 6 months of treatment with 1.2 mg/day of liraglutide, using a bolus of l-[1-13C]leucine followed by a 16-hour constant infusion.

RESULTS

Liraglutide reduced BMI (34.9 ± 4.7 vs 36.6 ± 4.9 kg/m2, P = 0.012), HbA1c (7.1 ± 1.1 vs 9.6 ± 2.6%, P = 0.003), HOMA-IR (5.5 ± 1.9 vs 11.6 ± 11.2, P = 0.003), fasting triglycerides (1.76 ± 0.37 vs 2.48 ± 0.69 mmol/l, P < 0.001) and triglycerides during kinetics (2.34 ± 0.81 vs 2.66 ± 0.65 mmol/l, P = 0.053). Plasma HDL cholesterol and adiponectin concentrations were unchanged (respectively 0.97 ± 0.26 vs 0.97 ± 0.19 mmol/l, P = 1; 3169 ± 1561 vs 2618 ± 1651 µg/l, P = 0.160), similar to triglyceride content in HDL (5.13 ± 1.73 vs 5.39 ± 1.07%, P = 0.386). Liraglutide modified neither HDL apoAI fractional catabolic rate (0.35 ± 0.11 vs 0.38 ± 0.11 pool/day, P = 0.375), nor its production rate (0.44 ± 0.13 vs 0.49 ± 0.15 g/l/day, P = 0.375), nor its plasma concentration (1.26 ± 0.19 vs 1.29 ± 0.14 g/l, P = 0.386).

CONCLUSION

Six months of treatment with 1.2 mg/day of liraglutide had no effect on the kinetics of HDL apoAI in patients with T2D. The lack of decrease in triglyceride content in HDL related to an only moderate decrease in triglyceridemia, probably greatly explains these results. Insufficient improvement of insulin sensitivity and adiponectinemia may also be implied.

Development of Syringaldehyde as an Agonist of the GLP-1 Receptor to Alleviate Diabetic Disorders in Animal Models

The phenolic aldehyde syringaldehyde (SA) has been shown to have an antihyperglycemic effect in diabetic rats due to increased glucose utilization and insulin sensitivity. To understand the direct effect of SA on the GLP-1 receptor, STZ-induced diabetic rats were used. The levels of pro-inflammatory cytokines, liver enzymes, and renal function were measured using specific ELISA kits. The mechanisms of SA effects were investigated using CHO-K1 cells, pancreatic Min-6 cells, and cardiomyocyte H9c2 cells. The results indicated that the antihyperglycemic effect of SA in diabetic rats was abolished by blocking the GLP-1 receptor with an antagonist. SA has a direct effect on the GLP-1 receptor when using CHO-K1 cells transfected with the exogenous GLP-1 receptor gene. In addition, SA stimulated insulin production in Min-6 cells by activating GLP-1 receptors. SA caused a dose-dependent rise in GLP-1 receptor mRNA levels in cardiac H9c2 cells. These in vitro results support the notion that SA has a direct effect on the GLP-1 receptor. Otherwise, SA inhibited the increase of pro-inflammatory cytokines, including interleukins and tumor TNF-α, in type 1 diabetic rats in a dose-dependent manner. Moreover, as with liraglutide, SA reduced plasma lipid profiles, including total cholesterol and triglyceride, in mixed diet-induced type 2 diabetic rats. Intriguingly, chronic treatment with SA (as with liraglutide) reversed the functions of both the liver and the kidney in these diabetic rats. SA displayed less efficiency in reducing body weight and food consumption compared to liraglutide. In conclusion, SA effectively activates GLP-1 receptors, resulting in a reduction in diabetic-related complications in rats. Therefore, it is beneficial to develop SA as a chemical agonist for clinical applications in the future.

Potential Mechanisms of the Protective Effects of the Cardiometabolic Drugs Type-2 Sodium-Glucose Transporter Inhibitors and Glucagon-like Peptide-1 Receptor Agonists in Heart Failure

Different multifactorial pathophysiological processes are involved in the development of heart failure (HF), including neurohormonal dysfunction, the hypertrophy of cardiomyocytes, interstitial fibrosis, microvascular endothelial inflammation, pro-thrombotic states, oxidative stress, decreased nitric oxide (NO) bioavailability, energetic dysfunction, epicardial coronary artery lesions, coronary microvascular rarefaction and, finally, cardiac remodeling. While different pharmacological strategies have shown significant cardiovascular benefits in HF with reduced ejection fraction (HFrEF), there is a residual unmet need to fill the gap in terms of knowledge of mechanisms and efficacy in the outcomes of neurohormonal agents in HF with preserved ejection fraction (HFpEF). Recently, type-2 sodium-glucose transporter inhibitors (SGLT2i) have been shown to contribute to a significant reduction in the composite outcome of HF hospitalizations and cardiovascular mortality across the entire spectrum of ejection fraction. Moreover, glucagon-like peptide-1 receptor agonists (GLP1-RA) have demonstrated significant benefits in patients with high cardiovascular risk, excess body weight or obesity and HF, in particular HFpEF. In this review, we will discuss the biological pathways potentially involved in the action of SGLT2i and GLP1-RA, which may explain their effective roles in the treatment of HF, as well as the potential implications of the use of these agents, also in combination therapies with neurohormonal agents, in the clinical practice.

Ceramides are decreased after liraglutide treatment in people with type 2 diabetes: a post hoc analysis of two randomized clinical trials

BACKGROUND

Specific ceramides have been identified as risk markers for cardiovascular disease (CVD) years before onset of disease. Treatment with the glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide has been shown to induce beneficial changes in the lipid profile and reduce the risk of CVD. Reducing lipotoxic lipids with an antidiabetic drug therapy could be a path towards precision medicine approaches for the treatment of complications to diabetes. In this post-hoc study, an investigation was carried out on the effect of liraglutide on CVD-risk associated ceramides in two randomized clinical trials including participants with type 2 diabetes (T2D).

METHODS

This study analyzed plasma samples from two independent randomized placebo-controlled clinical trials. The first trial, Antiproteinuric Effects of Liraglutide Treatment (LirAlbu12) followed a crossover design where 27 participants were treated for 12 weeks with either liraglutide (1.8 mg/d) or placebo, followed by a four-week washout period, and then another 12 weeks of the other treatment. The second clinical trial, Effect of Liraglutide on Vascular Inflammation in Type-2 Diabetes (LiraFlame26), lasted for 26 weeks and followed a parallel design, where 102 participants were randomized 1:1 to either liraglutide or placebo. Heresix prespecified plasma ceramides were measured using liquid chromatography mass spectrometry and assessed their changes using linear mixed models. Possible confounders were assessed with mediation analyses.

RESULTS

In the LiraFlame26 trial, 26-week treatment with liraglutide resulted in a significant reduction of two ceramides associated with CVD risk, C16 Cer and C24:1 Cer (p < 0.05) compared to placebo. None of the remaining ceramides showed statistically significant changes in response to liraglutide treatment compared to placebo. Significant changes in ceramides were not found after 12-weeks of liraglutide treatment in the LirAlbu12 trial. Mediation analyses showed that weight loss did not affect ceramide reduction.

CONCLUSIONS

It was demonstrated that treatment with liraglutide resulted in a reduction in C16 Cer and C24:1 Cer after 26 weeks of treatment. These findings suggest the GLP-1RA can be used to modulate ceramides in addition to its other properties.

TRIAL REGISTRATION

Clinicaltrial.gov identifier: NCT02545738 and NCT03449654.

The association between circulatory, local pancreatic PCSK9 and type 2 diabetes mellitus: The effects of antidiabetic drugs on PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent modulator of cholesterol metabolism and plays a crucial role in the normal functioning of pancreatic islets and the progression of diabetes. Islet autocrine PCSK9 deficiency can lead to the enrichment of low-density lipoprotein (LDL) receptor (LDLR) and excessive LDL cholesterol (LDL-C) uptake, subsequently impairing the insulin secretion in β-cells. Circulatory PCSK9 levels are primarily attributed to hepatocyte secretion. Notably, anti-PCSK9 strategies proposed for individuals with hypercholesterolemia chiefly target liver-derived PCSK9; however, these anti-PCSK9 strategies have been associated with the risk of new-onset diabetes mellitus (NODM). In the current review, we highlight a new direction in PCSK9 inhibition therapy strategies: screening candidates for anti-PCSK9 from the drugs used in type 2 diabetes mellitus (T2DM) treatment. We explored the association between circulating, local pancreatic PCSK9 and T2DM, as well as the relationship between PCSK9 monoclonal antibodies and NODM. We discussed the emergence of artificial and natural drugs in recent years, exhibiting dual benefits of antidiabetic activity and PCSK9 reduction, confirming that the diverse effects of these drugs may potentially impact the progression of diabetes and associated disorders, thereby introducing novel avenues and methodologies to enhance disease prognosis.

Insight into the role of PCSK9 in glucose metabolism

Diabetes mellitus (DM) is strongly associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Proprotein convertase subtilisin/kexin type 9 (PCSK9) was recently identified as an important regulator of circulating low-density lipoprotein-cholesterol (LDL-C) levels via degradation of the LDL receptor, proving to be a valid target to improve lipoprotein profiles and cardiovascular outcomes in patients with ASCVD. Beyond LDL receptor processing and cholesterol homeostasis, the PCSK9 protein has recently been verified to be associated with glucose metabolism. Importantly, clinical trials suggest that treatment with PCSK9 inhibitors for patients with DM is more effective. Hence, in this review, we summarize the current findings derived from experimental, preclinical, and clinical studies regarding the association between PCSK9 and glucose metabolism, including the relationship of PCSK9 genetic mutations to glucose metabolism and diabetes, the link between plasma PCSK9 concentrations and glucose metabolic parameters, the effects of glucose-lowering drugs on plasma PCSK9 levels and the impacts of PCSK9 inhibitors on cardiovascular outcomes of patients with DM. Clinically, exploring this field may improve our understanding regarding the roles of PCSK9 in glucose metabolism and may offer an in-depth interpretation of how PCSK9 inhibitors exert effects on the treatment of patients with DM.

Glucagon-like Peptide-1 Receptor-based Therapeutics for Metabolic Liver Disease

Glucagon-like peptide-1 (GLP-1) controls islet hormone secretion, gut motility, and body weight, supporting development of GLP-1 receptor agonists (GLP-1RA) for the treatment of type 2 diabetes (T2D) and obesity. GLP-1RA exhibit a favorable safety profile and reduce the incidence of major adverse cardiovascular events in people with T2D. Considerable preclinical data, supported by the results of clinical trials, link therapy with GLP-RA to reduction of hepatic inflammation, steatosis, and fibrosis. Mechanistically, the actions of GLP-1 on the liver are primarily indirect, as hepatocytes, Kupffer cells, and stellate cells do not express the canonical GLP-1R. GLP-1RA reduce appetite and body weight, decrease postprandial lipoprotein secretion, and attenuate systemic and tissue inflammation, actions that may contribute to attenuation of metabolic-associated fatty liver disease (MAFLD). Here we discuss evolving concepts of GLP-1 action that improve liver health and highlight evidence that links sustained GLP-1R activation in distinct cell types to control of hepatic glucose and lipid metabolism, and reduction of experimental and clinical nonalcoholic steatohepatitis (NASH). The therapeutic potential of GLP-1RA alone, or in combination with peptide agonists, or new small molecule therapeutics is discussed in the context of potential efficacy and safety. Ongoing trials in people with obesity will further clarify the safety of GLP-1RA, and pivotal studies underway in people with NASH will define whether GLP-1-based medicines represent effective and safe therapies for people with MAFLD.

Exenatide prevents statin-related LDL receptor increase and improves insulin secretion in pancreatic beta cells (1.1E7) in a protein kinase A-dependent manner

Statins are primary drugs in the treatment of hyperlipidemias. This group of drugs is known for its beneficial pleiotropic effects (e.g., reduction of inflammatory state). However, a growing body of evidence suggests its diabetogenic properties. The culpable mechanism is not completely understood and might be related to the damage to pancreatic beta cells. Therefore, we conceived an in vitro study to explore the impact of atorvastatin on pancreatic islet beta cells line (1.1.E7). We evaluated the influence on viability, insulin, low-density lipoprotein (LDL) receptor, and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression. A significant drop in mRNA for proinsulin and insulin expression was noted. Concurrently, a rise in LDL receptor at the protein level in cells exposed to atorvastatin was noted. Further experiments have shown that exenatide - belonging to glucagon-like peptide 1 (GLP-1) analogs that are used in a treatment of diabetes and known for its weight reducing properties - can alleviate the observed alterations. In this case, the mechanism of action of exenatide was dependent on a protein kinase A pathway. In conclusion, our results support the hypothesis that statin may have diabetogenic properties, which according to our study is related to reduced insulin expression. The concomitant use of GLP-1 receptor agonist seemed to successfully revert insulin expression.

Protection against stroke with glucagon-like peptide-1 receptor agonists: a comprehensive review of potential mechanisms

Several randomized controlled trials have demonstrated the benefits of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on ischemic stroke in patients with diabetes. In this review, we summarize and discuss the potential mechanisms of stroke protection by GLP-1RAs. GLP-1RAs exert multiple anti-atherosclerotic effects contributing to stroke prevention such as enhanced plaque stability, reduced vascular smooth muscle proliferation, increased nitric oxide, and improved endothelial function. GLP-1RAs also lower the risk of stroke by reducing traditional stroke risk factors including hyperglycemia, hypertension, and dyslipidemia. Independently of these peripheral actions, GLP-1RAs show direct cerebral effects in animal stroke models, such as reduction of infarct volume, apoptosis, oxidative stress, neuroinflammation, excitotoxicity, blood-brain barrier permeability, and increased neurogenesis, neuroplasticity, angiogenesis, and brain perfusion. Despite these encouraging findings, further research is still needed to understand more thoroughly the mechanisms by which GLP-1RAs may mediate stroke protection specifically in the human diabetic brain.

Quantitative NMR-Based Lipoprotein Analysis Identifies Elevated HDL-4 and Triglycerides in the Serum of Alzheimer’s Disease Patients

Alzheimer’s disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative lipoprotein analysis in a local cohort of cognitively impaired elderly and control subjects using standardized nuclear magnetic resonance (NMR) spectroscopy. A commercially available quantitative NMR-based assay covering 112 lipoprotein main and subtype variables was used to investigate blood serum samples from a moderate cohort size of 161 persons (71 female, 90 male), including measures of quality control. Additionally, clinical metadata and cerebrospinal fluid AD biomarkers were collected and used for analysis. High-density lipoprotein (HDL) HDL-4 subfraction levels were mostly high in female individuals with mild cognitive impairment (MCI), followed by AD. Low-density lipoprotein (LDL) LDL-2 cholesterol was slightly elevated in male AD patients. HDL-2 apolipoprotein Apo-A1, HDL-2 phospholipids, and HDL-3 triglycerides were highly abundant in AD and MCI women compared to men. When considering clinical biomarkers (Aβ, tau), very low-density lipoprotein (VLDL) VLDL-1 and intermediate-density lipoprotein (IDL) triglycerides were substantially higher in AD compared to MCI. In addition, triglyceride levels correlated positively with dementia. Different lipoprotein serum patterns were identified for AD, MCI, and control subjects. Interestingly, HDL-4 and LDL-2 cholesterol parameters revealed strong gender-specific changes in the context of AD-driven dementia. As gender-based comparisons were based on smaller sub-groups with a low n-number, several statistical findings did not meet the significance threshold for multiple comparisons testing. Still, our finding suggests that serum HDL-4 parameters and various triglycerides correlate positively with AD pathology which could be a read-out of extended lipids traveling through the blood-brain barrier, supporting amyloid plaque formation processes. Thereof, we see herein a proof of concept that this quantitative NMR-based lipoprotein assay can generate important and highly interesting data for refined AD diagnosis and patient stratification, especially when larger cohorts are available.

Effect of glucagon-like peptide-1 (GLP-1) analogues on epicardial adipose tissue: A meta-analysis

BACKGROUND AND AIMS

Glucagon-like peptide-1 (GLP-1) analogues reduce body fat and cardiovascular events in patients with type 2 diabetes. Accumulation of epicardial adipose tissue (EAT) is associated with increased cardio-metabolic risks and coronary events in type 2 diabetes.

METHODS

A systematic review and meta-analysis were performed from Glucagon-like peptide-1 analogues therapy on type 2 diabetes patients, reporting data from changes in EAT, after searching the PubMed/MEDLINE, Embase, Science Direct, Scopus, Google Scholar, and Cochrane databases.

RESULTS

It has been found a limited number of studies, a total of 4 studies (n = 160 patients with GLP-1 analogues therapy) were included in the final analysis. Pooled analysis revealed that GLP-1 analogues reduce EAT (MD: 1.83 mm [-2.50; -1.10]; P < 0.01). Compared with the patients before the treatment, the patients after the treatment had a smaller HbA1c (MD -1.10%[-1.80; -0.30]; p = 0.0143) and body mass index was reduced (MD -2.20 kg/m²[-3.70; -0.60]; p = 0.0058), GLP-1 therapy reduced low-density lipoprotein levels (MD-13.53 mg/dL [-21.74; -5.31]; p = 0.001) and reduced triglycerides levels significantly (MD -18.32 -28.20 mg/dL; -8.50); p = 0.0003).

CONCLUSIONS

This meta-analysis suggests that the amount of EAT is significantly reduced in T2D patients with Glucagon-like peptide-1 analogues.

Role of endogenous incretins in the regulation of postprandial lipoprotein metabolism

OBJECTIVE

Incretins are known to influence lipid metabolism in the intestine when administered as pharmacologic agents. The aggregate influence of endogenous incretins on chylomicron production and clearance is less clear, particularly in light of opposing effects of co-secreted hormones. Here, we tested the hypothesis that physiological levels of incretins may impact on production or clearances rates of chylomicrons and VLDL.

DESIGN AND METHODS

A group of 22 overweight/obese men was studied to determine associations between plasma levels of glucagon-like peptides 1 and 2 (GLP-1 and GLP-2) and glucose-dependent insulinotropic polypeptide (GIP) after a fat-rich meal and the production and clearance rates of apoB48- and apoB100-containing triglyceride-rich lipoproteins. Subjects were stratified by above- and below-median incretin response (area under the curve).

RESULTS

Stratification yielded subgroups that differed about two-fold in incretin response. There were neither differences in apoB48 production rates in chylomicrons or VLDL fractions nor in apoB100 or triglyceride kinetics in VLDL between men with above- vs below-median incretin responses. The men with above-median GLP-1 and GLP-2 responses exhibited higher postprandial plasma and chylomicron triglyceride levels, but this could not be related to altered kinetic parameters. No differences were found between incretin response subgroups and particle clearance rates.

CONCLUSION

We found no evidence for a regulatory effect of endogenous incretins on contemporaneous chylomicron or VLDL metabolism following a standardised fat-rich meal. The actions of incretins at pharmacological doses may not be reflected at physiological levels of these hormones.

Plasma proteomics reveals an improved cardio-metabolic profile in patients with type 2 diabetes post-liraglutide treatment

BACKGROUND

Diabetes mellitus is a chronic multisystem disease with a high global prevalence, including in Saudi Arabia. The Glucagon-like Peptide (GLP-1) receptor agonist liraglutide is known to lower glucose levels, reduce weight and improve cardiovascular outcome. However, mechanisms underlying the benefits of liraglutide treatment in patients with type 2 diabetes mellitus (T2DM) remain unclear.

METHODS

In the present study, a 2D-DIGE MALDI-TOF mass spectrometric approach combined with bioinformatics and network pathway analysis explore the plasma proteomic profile. The study involved 20 patients with T2DM with mean age of 54.4 ± 9.5 years and Hemoglobin A1c (HbA1c) between 8% and 11% (inclusive).

RESULTS

A statistically significant change (p < .006) was observed in HbA1c with no significant changes in body weight, renal function, or markers of dyslipidemia post-treatment with liraglutide. 2 D-DIGE gel analysis identified significant changes (⩾1.5-fold change, Analysis of variance (ANOVA), p ⩽ 0.05) in 72 proteins, (62 down and 10 up) in liraglutide pre-treatment compared to the post-treatment state. Proteins identified in our study were found to regulate metabolic processes including acute phase response proteins, enzymes, apolipoproteins with involvement of the inflammatory signaling pathways, NF-κB, AKT, and p38 MAPK.

CONCLUSION

Liraglutide treatment decreased levels of acute phase response that to reduce the systemic chronic inflammatory state and oxidative stress, and eventually improve the cardio-metabolic profile in these patients.

Liraglutide Lowers Palmitoleate Levels in Type 2 Diabetes. A Post Hoc Analysis of the LIRAFLAME Randomized Placebo-Controlled Trial

Background

Liraglutide is a glucose-lowering medication used to treat type 2 diabetes and obesity. It is a GLP-1 receptor agonist with downstream metabolic changes beyond the incretin system, such as reducing the risk of cardiovascular complications. The understanding of these changes is critical for improving treatment outcomes. Herein, we present a post hoc experimental analysis using metabolomic phenotyping to discover molecular mecphanisms in response to liraglutide.

Method

Plasma samples were obtained from The LiraFlame Study (ClinicalTrials.gov identifier: NCT03449654), a randomized double-blinded placebo-controlled clinical trial, including 102 participants with type 2 diabetes randomized to either liraglutide or placebo treatment for 26 weeks. Mass spectrometry-based metabolomics analyses were carried out on samples from baseline and the end of the trial. Metabolites (n=114) were categorized into pathways and linear mixed models were constructed to evaluate the association between changes in metabolites and liraglutide treatment.

Results

We found the free fatty acid palmitoleate was significantly reduced in the liraglutide group compared to placebo (adjusted for multiple testing p-value = 0.04). The activity of stearoyl-CoA desaturase-1 (SCD1), the rate limiting enzyme for converting palmitate into palmitoleate, was found significantly downregulated by liraglutide treatment compared to placebo (p-value = 0.01). These metabolic changes have demonstrated to be linked to insulin sensitivity and cardiovascular health.

Sexual Dimorphism in the Association of Serum Retinol-Binding Protein-4 With Long-Term Dynamic Metabolic Profiles in Non-Diabetes

OBJECTIVES

We aimed to investigate the association of circulating retinol-binding protein-4 (RBP4) levels with long-term cardiometabolic risk profiles and whether sex disparity mattered.

METHODS

We included 784 non-diabetic participants aged 40 years and above from a well-defined community-based cohort at baseline in 2005 and they were invited to attend the on-site follow-up examination for two consecutive times with 3-year intervals in 2008 and 2011, respectively. Serum RBP4 was measured at baseline, and the anthropometry and biochemical measurements were performed at each visit. Generalized estimating equation models were used to assess the association of serum RBP4 levels with the dynamic changes in adiposity and glucolipid profile.

RESULTS

Based on all the baseline and the 3- and 6-year follow-up data, baseline serum RBP4 levels (each 1-unit of log₁₀RBP4) were significantly associated with waist circumference [β=3.12, 95% confidence interval (CI) (0.77, 5.47), P=0.01], fasting, and 2-h post-loading glucose [β=0.26 (0.05, 0.47), P=0.02, and 1.70 (1.29, 2.12), P< 0.0001], serum triglycerides [β=0.75, 95% CI (0.54, 0.96), P< 0.0001], total cholesterol [β=0.47, 95% CI [0.23 0.70], P<0.0001), and marginally with body mass index (β=0.97, 95% CI (0.02, 1.93), P=0.046], in total participants, after adjusting potential confounders. The association of RBP4 with 2-h post-loading glucose was stronger in women than that in men [β=1.99, 95% CI (1.49, 2.50) vs. 0.61 (-0.14, 1.36), P for interaction=0.001]. The analysis of change in Z-score of cardiometabolic profiles corresponding to each 1-unit increment in log₁₀RBP4 showed consistent results.

CONCLUSIONS

Higher RBP4 levels are associated with longitudinal increase in adiposity and deteriorated glucolipid profile defined by repeated measurements. The associations differ in sex regarding to the 2-h post-loading glucose.

Oral GLP-1 analogue: perspectives and impact on atherosclerosis in type 2 diabetic patients

Cardiovascular events related to atherosclerosis are responsible for high morbidity and mortality among patients with type 2 diabetes. Improvement in care, especially in early stages, is crucial. Oral semaglutide, a glucagon-like peptide 1 analogue, controls blood glucose and results in significant body weight loss in patients with type 2 diabetes. Beyond these well-known effects, an interesting aspect of this drug is its antiatherogenic activity, which should be further explored in clinical practice. This paper reviews the evidence related to oral semaglutide decreasing cardiovascular risk in patients with type 2 diabetes, focusing on the drug's antiatherosclerotic properties. The glucagon-like peptide 1 analogue restores endothelial dysfunction, induces vasodilatation, and reduces plasma lipids. Oral semaglutide showed cardiovascular safety profile, with significant reduced risk of death from cardiovascular events. Based on current data, clinicians should consider oral semaglutide for type 2 diabetes management.

Association of serum apolipoprotein B with retinal neurovascular structural alterations in patients with type 2 diabetes: an optical coherence tomography angiography study

PURPOSE

To investigate the association of serum apoB concentrations with retinal neurovascular structural alterations in type 2 diabetes patients without clinically visible retinopathy.

METHODS

Eyes with no clinically visible diabetic retinopathy (DR) from diabetic patients with or without dyslipidemia were included. Changes in retinal neural structures, including the ganglion cell layer (GCL) and peripapillary retinal nerve fiber layer (RNFL) thicknesses, and microvascular metrics, including macular vessel density (VD) and perfusion density (PD) of the superficial capillary plexus, were measured with optical coherence tomography angiography (OCTA). Correlations between inner retinal layer thickness and OCTA metrics were analyzed. The association of serum apoB and diabetic retinal neurovascular structures was identified with regression analysis.

RESULTS

A total of 148 eyes in the diabetes group (n = 74) and dyslipidemia group (n = 74) were enrolled. GCL and RNFL thicknesses in patients in the dyslipidemia group were significantly thinner than those in the diabetes group (all p < 0.025). The total area of the VD and PD in the dyslipidemia group was also decreased compared to that of the diabetes group (p < 0.05) and was found to correlate with GCL and RNFL (all p < 0.01) thicknesses in all diabetic patients. Serum apoB levels were positively related to low-density lipoprotein (LDL) and total cholesterol (TC). Moreover, the average GCL thickness was significantly associated with serum apoB levels (all p < 0.05).

CONCLUSIONS

GCL and RNFL thinning was significantly correlated with decreased retinal blood flow in diabetic patients with dyslipidemia. Strictly controlling serum lipids, especially apoB levels, might be an effective strategy for DR treatment.

The Reciprocal Relationship between LDL Metabolism and Type 2 Diabetes Mellitus

Type 2 diabetes mellitus and insulin resistance feature substantial modifications of the lipoprotein profile, including a higher proportion of smaller and denser low-density lipoprotein (LDL) particles. In addition, qualitative changes occur in the composition and structure of LDL, including changes in electrophoretic mobility, enrichment of LDL with triglycerides and ceramides, prolonged retention of modified LDL in plasma, increased uptake by macrophages, and the formation of foam cells. These modifications affect LDL functions and favor an increased risk of cardiovascular disease in diabetic individuals. In this review, we discuss the main findings regarding the structural and functional changes in LDL particles in diabetes pathophysiology and therapeutic strategies targeting LDL in patients with diabetes.

Electronic health record-based genome-wide meta-analysis provides insights on the genetic architecture of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a complex disease linked to several chronic diseases. We aimed at identifying genetic variants associated with NAFLD and evaluating their functional consequences. We performed a genome-wide meta-analysis of 4 cohorts of electronic health record-documented NAFLD in participants of European ancestry (8,434 cases and 770,180 controls). We identify 5 potential susceptibility loci for NAFLD (located at or near GCKR, TR1B1, MAU2/TM6SF2, APOE, and PNPLA3). We also report a potentially causal effect of lower LPL expression in adipose tissue on NAFLD susceptibility and an effect of the FTO genotype on NAFLD. Positive genetic correlations between NAFLD and cardiometabolic diseases and risk factors such as body fat accumulation/distribution, lipoprotein-lipid levels, insulin resistance, and coronary artery disease and negative genetic correlations with parental lifespan, socio-economic status, and acetoacetate levels are observed. This large GWAS meta-analysis reveals insights into the genetic architecture of NAFLD.

Unravelling lipoprotein metabolism with stable isotopes: tracing the flow

Dysregulated lipoprotein metabolism is a major cause of atherosclerotic cardiovascular disease (ASCVD). Use of stable isotope tracers and compartmental modelling have provided deeper understanding of the mechanisms underlying lipid disorders in patients at high risk of ASCVD, including familial hypercholesterolemia (FH), elevated lipoprotein(a) [Lp(a)] and metabolic syndrome (MetS). In patients with FH, deficiency in low-density lipoprotein (LDL) receptor activity not only impairs the catabolism of LDL, but also induces hepatic overproduction and decreases catabolism of triglyceride-rich lipoproteins (TRLs). Patients with elevated Lp(a) are characterized by increased hepatic secretion of Lp(a) particles. Atherogenic dyslipidemia in MetS patients relates to a combination of overproduction of very-low density lipoprotein-apolipoprotein (apo) B-100, decreased catabolism of apoB-100-containing particles, and increased catabolism of high-density lipoprotein-apoA-I particles, as well as to impaired clearance of TRLs in the postprandial state. Kinetic studies show that weight loss, fish oils, statins and fibrates have complementary modes of action that correct atherogenic dyslipidemia. Defining the kinetic mechanisms of action of proprotein convertase subtilisin/kexin type 9 and angiopoietin-like 3 inhibitors on lipid and lipoprotein mechanism in dyslipidemic subjects will further our understanding of these therapies in decreasing the development of ASCVD. "Everything changes but change itself. Everything flows and nothing remains the same... You cannot step twice into the same river, for other waters and yet others go flowing ever on." Heraclitus (c.535- c. 475 BCE).

Liraglutide reduces plasma PCSK9 in patients with type 2 diabetes not treated with statins

AIM

Dyslipidaemia in type 2 diabetes mellitus (T2DM), which increases cardiovascular risk, includes abnormal metabolism of low-density lipoproteins (LDL). Our group has recently shown that liraglutide increases LDL catabolism in patients with T2DM and that it reduces the expression of PCSK9 (a major inhibitor of LDL-receptor expression) in vitro and in mice. This prompted us to study the effect of liraglutide on plasma PCSK9 level in patients with T2DM.

METHODS

We studied prospectively 82 patients with T2DM (51 without statins, 31 with statins). Plasma PCSK9 and plasma lipids were measured before and six months after the initiation of a treatment with liraglutide at a dose of 1.2 mg/day.

RESULTS

Plasma PCSK9 was significantly reduced by liraglutide treatment (214.9 ± 56.4 vs 244.5 ± 99.2 ng/ml, P = 0.024) in patients not on statins, but not in patients treated with statins (301.1 ± 91.5 vs 281.2 ± 96.9 ng/ml, P = 0.41). In patients not on statins, a very significant 17% decrease in plasma PCSK9 was observed in patients with baseline haemoglobin A1c (HbA1c) < 10% (n = 33; mean = -45.0 ng/ml, P = 0.013), when it was not observed in patients with baseline HbA1c ≥ 10% (n = 18; mean = +5.2 ng/ml, P = 0.75). In multivariate analysis, baseline HbA1c was an independent factor associated with plasma PCSK9 reduction, in patients not on statins.

CONCLUSION

Treatment with liraglutide induces a significant reduction of plasma PCSK9 in patients with T2DM not on statins. This is in line with the acceleration of LDL catabolism that has been observed with liraglutide. However, this decrease in plasma PCSK9 is significantly influenced by glycaemic control and is not observed in patients with poorly controlled T2DM.