The effect of liraglutide and sitagliptin on oxidative stress in persons with type 2 diabetes

Glucagon-like peptide-1 receptor agonists: new strategies and therapeutic targets to treat atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of cardiovascular mortality and is increasingly prevalent in our population. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) can safely and effectively lower glucose levels while concurrently managing the full spectrum of ASCVD risk factors and improving patients' long-term prognosis. Several cardiovascular outcome trials (CVOTs) have been carried out to further investigate the cardiovascular benefits of GLP-1RAs. Analyzing data from CVOTs can provide insights into the pathophysiologic mechanisms by which GLP-1RAs are linked to ASCVD and define the use of GLP-1RAs in clinical practice. Here, we discussed various mechanisms hypothesized in previous animal and preclinical human studies, including blockade of the production of adhesion molecules and inflammatory factors, induction of endothelial cells' synthesis of nitric oxide, protection of mitochondrial function and restriction of oxidative stress, suppression of NOD-like receptor thermal protein domain associated protein three inflammasome, reduction of foam cell formation and macrophage inflammation, and amelioration of vascular smooth muscle cell dysfunction, to help explain the cardiovascular benefits of GLP-1RAs in CVOTs. This paper provides an overview of the clinical research, molecular processes, and possible therapeutic applications of GLP-1RAs in ASCVD, while also addressing current limitations in the literature and suggesting future research directions.

Cardiovascular benefits of SGLT2 inhibitors and GLP-1 receptor agonists through effects on mitochondrial function and oxidative stress

Overloaded glucose levels in several metabolic diseases such as type 2 diabetes (T2D) can lead to mitochondrial dysfunction and enhanced production of reactive oxygen species (ROS). Oxidative stress and altered mitochondrial homeostasis, particularly in the cardiovascular system, contribute to the development of chronic comorbidities of diabetes. Diabetes-associated hyperglycemia and dyslipidemia can directly damage vascular vessels and lead to coronary artery disease or stroke, and indirectly damage other organs and lead to kidney dysfunction, known as diabetic nephropathy. The new diabetes treatments include Na+-glucose cotransporter 2 inhibitors (iSGLT2) and glucagon-like 1 peptide receptor agonists (GLP-1RA), among others. The iSGLT2 are oral anti-diabetic drugs, whereas GLP-1RA are preferably administered through subcutaneous injection, even though GLP-1RA oral formulations have recently become available. Both therapies are known to improve both carbohydrate and lipid metabolism, as well as to improve cardiovascular and cardiorenal outcomes in diabetic patients. In this review, we present an overview of current knowledge on the relationship between oxidative stress, mitochondrial dysfunction, and cardiovascular therapeutic benefits of iSGLT2 and GLP-1RA. We explore the benefits, limits and common features of the treatments and remark how both are an interesting target in the prevention of obesity, T2D and cardiovascular diseases, and emphasize the lack of a complete understanding of the underlying mechanism of action.

SGLT2i relieve proteinuria in diabetic nephropathy patients potentially by inhibiting renal oxidative stress rather than through AGEs pathway

AIMS

To estimate the effects of the sodium-glucose cotransporter 2 inhibitor (SGLT2i) on proteinuria and oxidative stress expression in type 2 diabetes patients.

MATERIALS AND METHODS

68 patients with type 2 diabetes mellitus (T2DM) were divided into three groups according urinary albumin-to-creatinine ratio (UACR), including T2DM with non-albuminuria group (UACR < 30 mg/g), T2DM with microalbuminuria group (30 ≤ UACR ≤ 300 mg/g), T2DM with macroalbuminuria group (UACR>300 mg/g). They all received SGLT2 inhibitors (SGLT2i) treatment for 12 weeks. The expression of advanced glycation end products (AGEs) in plasma and 8-hydroxy-2-deoxyguanosine (8-OHdG) in urine were measured as indications of oxidative stress. The 24-hour urine samples were collected to measure the concentration of proteinuria and 8-OHdG before and after 12 weeks SGLT2i treatment. Plasma renin activity (PRA), angiotensin II (Ang II) and Aldosterone (ALD) were measured to evaluate renin angiotensin aldosterone system (RASS) levels.

RESULTS

After 12 weeks SGLT2 inhibitors treatment, the median values of 24-hour proteinuria decreased in macroalbuminuria compared to baseline (970 vs. 821 mg/d, P = 0.006). The median values of AGEs and 8-OHdG decreased in microalbuminuria and macroalbuminuria groups when compared to baseline, AGEs (777 vs. 136 ug/ml, P = 0.003) and (755 vs. 210 ug/ml, P = 0.001), 8-OHdG (8.00 vs. 1.88 ng/ml, P = 0.001) and (11.18 vs. 1.90 ng/ml, P < 0.001), respectively. Partial correlations showed that 8-OHdG were relevant to the baseline 24-h proteinuria (r = 0.389, p = 0.001), the reduction of OHdG (Δ8-OHdG) were positively correlated with the decrease of 24-h proteinuria (Δ24-h proteinuria) after 12 weeks of SGLT2i treatment (r = 0.283, P = 0.031). There was no significant correlation between 24-h proteinuria and AGEs in baseline (r = -0.059, p = 0.640) as well as between ΔAGEs and Δ24-h proteinuria (r = 0.022, p = 0.872) after12 weeks of SGLT2i treatment in T2DM patients.

CONCLUSIONS

SGLT2i may reduce proteinuria in diabetic nephropathy patients, potentially by inhibiting renal oxidative stress, but not through the AGEs pathway and does not induce RAAS activation.

TRIAL REGISTRATION

This clinical trial was registered on 15/10/2019, in ClinicalTrials.gov, and the registry number is NCT04127084.

Effects of Two- and Twelve-Weeks Sodium-Glucose Cotransporter 2 Inhibition on DNA and RNA Oxidation: Two Randomized, Placebo-Controlled Trials

Animal studies have shown that SGLT2 inhibition decreases oxidative stress, which may explain the cardiovascular protective effects observed following SGLT2 inhibition treatment. Thus, we investigated the effects of two and twelve weeks SGLT2 inhibition on DNA and RNA oxidation. Individuals with type 2 diabetes (n = 31) were randomized to two weeks of treatment with the SGLT2 inhibitor empagliflozin treatment (25 mg once daily) or placebo. The primary outcome was changes in DNA and RNA oxidation measured as urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), respectively. In another trial, individuals with type 2 diabetes (n = 35) were randomized to twelve weeks of dapagliflozin treatment (10 mg once daily) or placebo in a crossover study. Changes in urinary excretion of 8-oxodG and 8-oxoGuo were investigated as a post-hoc analysis. Compared with placebo treatment, two weeks of empagliflozin treatment did not change urinary excretion of 8-oxodG (between-group difference: 0.3 nmol/24-hour (95% CI: -4.2 to 4.8)) or 8-oxoGuo (1.3 nmol/24-hour (95% CI: -4.7 to 7.3)). From a mean baseline 8-oxodG/creatinine urinary excretion of 1.34 nmol/mmol, dapagliflozin-treated individuals changed 8-oxodG/creatinine by -0.17 nmol/mmol (95% CI: -0.29 to -0.04) following twelve weeks of treatment, whereas placebo-treated individuals did not change 8-oxodG/creatinine (within-group effect: 0.10 nmol/mmol (95% CI: -0.02 to 0.22)) resulting in a significant between-group difference (P = 0.01). Urinary excretion of 8-oxoGuo was unaffected by dapagliflozin treatment. In conclusion, two weeks of empagliflozin treatment did not change DNA or RNA oxidation. However, a post-hoc analysis revealed that longer term dapagliflozin treatment decreased DNA oxidation. Clinicaltrials.gov: NCT02890745 and NCT02914691.HighlightsPlasma ferritin correlated with DNA and RNA oxidation in individuals with T2DTwelve weeks dapagliflozin treatment decreased DNA oxidationDapagliflozin and empagliflozin treatment did not change RNA oxidationLipid peroxidation was unaffected by two weeks empagliflozin treatment.

Early Detection Is the Best Prevention-Characterization of Oxidative Stress in Diabetes Mellitus and Its Consequences on the Cardiovascular System

Previous studies demonstrated an important role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) in diabetic patients due to hyperglycemia. CVD remains the leading cause of premature death in the western world. Therefore, diabetes mellitus-associated oxidative stress and subsequent inflammation should be recognized at the earliest possible stage to start with the appropriate treatment before the onset of the cardiovascular sequelae such as arterial hypertension or coronary artery disease (CAD). The pathophysiology comprises increased reactive oxygen and nitrogen species (RONS) production by enzymatic and non-enzymatic sources, e.g., mitochondria, an uncoupled nitric oxide synthase, xanthine oxidase, and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Considering that RONS originate from different cellular mechanisms in separate cellular compartments, adequate, sensitive, and compartment-specific methods for their quantification are crucial for early detection. In this review, we provide an overview of these methods with important information for early, appropriate, and effective treatment of these patients and their cardiovascular sequelae.