Canagliflozin, an Inhibitor of the Na+-Coupled D-Glucose Cotransporter, SGLT2, Inhibits Astrocyte Swelling and Brain Swelling in Cerebral Ischemia

Central SGLT2 mediate sympathoexcitation in hypertensive heart failure via attenuating subfornical organ endothelial cGAS ubiquitination to amplify neuroinflammation: Molecular mechanism behind sympatholytic effect of Empagliflozin

BACKGROUND

Sodium/glucose co-transporter 2 (SGLT2) inhibitors have transformed heart failure (HF) treatment, offering sympatholytic effects whose mechanisms are not fully understood. Our previous studies identified Cyclic GMP-AMP synthase (cGAS)-derived neuroinflammation in the Subfornical organ (SFO) as a promoter of sympathoexcitation, worsening myocardial remodeling in HF. This research explored the role of central SGLT2 in inducing endothelial cGAS-driven neuroinflammation in the SFO during HF and assessed the impact of SGLT2 inhibitors on this process.

METHODS

Hypertensive HF was induced in mice via Angiotensin II infusion for four weeks. SGLT2 expression and localization in the SFO were determined through immunoblotting and double-immunofluorescence staining. AAV9-TIE-shRNA (SGLT2) facilitated targeted SGLT2 knockdown in SFO endothelial cells (ECs), with subsequent analyses via immunoblotting, staining, and co-immunoprecipitation to investigate interactions with cGAS, mitochondrial alterations, and pro-inflammatory pathway activation. Renal sympathetic nerve activity and heart rate variability were measured to assess sympathetic output, alongside evaluations of cardiac function in HF mice.

RESULTS

In HF model mice, SGLT2 levels are markedly raised in SFO ECs, disrupting mitochondrial function and elevating oxidative stress. SGLT2 knockdown preserved mitochondrial integrity and function, reduced inflammation, and highlighted the influence of SGLT2 on mitochondrial health. SGLT2's interaction with cGAS prevented its ubiquitination and degradation, amplifying neuroinflammation and HF progression. Conversely, Empagliflozin counteracted these effects, suggesting that targeting the SGLT2-cGAS interaction as a novel HF treatment avenue.

CONCLUSION

This study revealed that SGLT2 directly reduced cGAS degradation in brain ECs, enhancing neuroinflammation in the SFO, and promoting sympathoexcitation and myocardial remodeling. The significance of the central SGLT2-cGAS interaction in cardiovascular disease mechanisms is emphasized.

Sodium-glucose cotransporter protein 2 inhibition, plasma proteins, and ischemic stroke: A mediation Mendelian randomization and colocalization study

PURPOSE

To determine the effect of the sodium-glucose cotransporter protein 2 (SGLT2) inhibition on ischemic stroke (IS) and investigate the circulating proteins that mediate the effects of SGLT2 inhibition on IS.

METHODS

The effects of SGLT2 inhibition on IS were evaluated using two-sample Mendelian randomization (MR) analyses. The 4,907 circulating proteins from the plasma proteome were assessed to identify potential mediators. Sensitivity, colocalization, and external validation analyses were conducted to validate critical findings. MR analyses were also used to evaluate the associations of SGLT2 inhibition with magnetic resonance imaging (MRI)-based biomarkers and functional prognoses post-IS.

RESULTS

SGLT2 inhibition was significantly associated with decreased risks of IS (odds ratio (OR): 0.39, 95 % confidence interval (CI): 0.25-0.61, p = 3.53 × 10-5) and cardioembolic stroke (OR: 0.16, 95 % CI: 0.07-0.37, p = 1.82 × 10-5); the effect of SGLT2 inhibition on IS was indirectly mediated through pathways involving tryptophanyl-transfer RNA synthetase (WARS) (β:0.08, 95 % CI:0.15 - -0.01, p = 0.034) and matrix metalloproteinase 12 (MMP12) (β:0.06, 95 % CI:0.12 - -0.01, p = 0.016), with mediation proportions of 8.2 % and 6.8 %, respectively. The external validation confirmed the WARS mediating effect. In addition, the sensitivity and colocalization analyses and MR analyses of MRI biomarker-based and functional prognostic outcomes supported these results.

CONCLUSION

In this study, we demonstrated from a genetic perspective that SGLT2 inhibitors prevent the development of IS and improve functional prognostic outcomes and brain microstructural integrity. WARS and MMP12 may act as potential mediators, presenting a novel approach for IS intervention.

The SGLT2 inhibitor empagliflozin exerts neuroprotective effect against hydrogen peroxide-induced toxicity on primary neurons

Oxidative stress has been implicated in several chronic pathological conditions, leading to cell death and injury. Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) have several overlapping mechanisms as they are both characterized by increased oxidative stress, inflammation, insulin resistance, and autophagy dysfunction. The objective of this study was to elucidate the possible neuroprotective effect of empagliflozin, a sodium-glucose co-transporter 2 inhibitor (SGLT2i), against hydrogen peroxide-induced neurotoxicity in primary hippocampal neurons derived from wild-type (WT) and transgenic AD rats (TgF344-AD). An in vitro oxidative stress model was established using hydrogen peroxide to induce damage to neurons. Empagliflozin pretreatment was tested on this model initially through a cell viability assay. Flow cytometry and cell sorting were employed to discriminate the apoptotic and necrotic neuronal cell populations. Finally, the morphological and morphometric features of the neurons, including dendritic length and spine density, were evaluated using the SNT ImageJ plug-in following immunostaining with GFP. Sholl analysis was used to evaluate the impact of empagliflozin and hydrogen peroxide on dendritic arborization. Empagliflozin tended to ameliorate hydrogen peroxide-induced toxicity in primary neurons derived from WT rats and led to the preservation of dendritic spine density in both WT and TgF344-AD neurons (one-way ANOVA, p < 0.05). A modest improvement in dendrites' length was also observed. Empagliflozin pretreatment can partially mitigate dendritic and spine alterations induced by hydrogen peroxide in primary neurons. These results underscore the impact of empagliflozin on neuronal morphology and highlight its potential as a candidate for the treatment and/or prevention of AD.

Causal relationship between novel antidiabetic drugs and ischemic stroke: a drug-targeted Mendelian randomization study

Background

The escalating global economic burden of ischemic stroke poses a significant public health challenge amid global aging trends. The broad therapeutic efficacy of new antidiabetic drugs may offer new options in the prevention and treatment of ischemic stroke. Consistent conclusions regarding the relationship between novel antidiabetic agents and the risk of ischemic stroke remain elusive, and the causal relationship deserves further investigation.

Materials and methods

Three novel antidiabetic drug targets were selected, and cis-expression quantitative trait loci (cis-eQTL) were screened as instrumental variables. Genetic association data for ischemic stroke were obtained from the Genome-wide Association Study (GWAS) database. Mendelian randomization (MR) analysis, facilitated by R software, calculated MR estimates for each single nucleotide polymorphism (SNP), and meta-analysis was performed using five methods. To ensure robustness, sensitivity analyses, heterogeneity analyses, horizontal pleiotropy analyses, and co-localization analyses were conducted for significant MR associations.

Results

Three eQTLs for antidiabetic drug genes served as instrumental variables, utilizing a GWAS dataset comprising 34,217 cases and 406,111 controls for ischemic stroke. Genetic variants in glucagon-like peptide-1 receptor agonists (GLP-1 RA) targets exhibited a positive correlation with ischemic stroke risk (OR 1.06, 95% CI 1.04-1.08, P = 0.000), while genetic variation in dipeptidyl peptidase 4 inhibitors (DPP-4i) targets showed a negative association with ischemic stroke risk (OR 0.93, 95% CI 0.89-0.97, P = 0.003). Sensitivity analyses supported robust conclusions, revealing no heterogeneity or horizontal pleiotropy.

Conclusion

This study found that GLP-1 RA and DPP-4i were associated with an increased risk of ischemic stroke by MR analysis. Although sensitivity analyses provide support for this result, it contradicts previous knowledge. Therefore, the results of this study still need to treated with caution. Updated and more in-depth GWAS data and high-quality real-world data are expected to validate the results.

The SGLT2 inhibitor Empagliflozin promotes post-stroke functional recovery in diabetic mice

Type-2 diabetes (T2D) worsens stroke recovery, amplifying post-stroke disabilities. Currently, there are no therapies targeting this important clinical problem. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are potent anti-diabetic drugs that also efficiently reduce cardiovascular death and heart failure. In addition, SGLT2i facilitate several processes implicated in stroke recovery. However, the potential efficacy of SGLT2i to improve stroke recovery in T2D has not been investigated. Therefore, we determined whether a post-stroke intervention with the SGLT2i Empagliflozin could improve stroke recovery in T2D mice. T2D was induced in C57BL6J mice by 8 months of high-fat diet feeding. Hereafter, animals were subjected to transient middle cerebral artery occlusion and treated with vehicle or the SGLTi Empagliflozin (10 mg/kg/day) starting from 3 days after stroke. A similar study in non diabetic mice was also conducted. Stroke recovery was assessed using the forepaw grip strength test. To identify potential mechanisms involved in the Empagliflozin-mediated effects, several metabolic parameters were assessed. Additionally, neuronal survival, neuroinflammation, neurogenesis and cerebral vascularization were analyzed using immunohistochemistry/quantitative microscopy. Empagliflozin significantly improved stroke recovery in T2D but not in non-diabetic mice. Improvement of functional recovery was associated with lowered glycemia, increased serum levels of fibroblast growth factor-21 (FGF-21), and the normalization of T2D-induced aberration of parenchymal pericyte density. The global T2D-epidemic and the fact that T2D is a major risk factor for stroke are drastically increasing the number of people in need of efficacious therapies to improve stroke recovery. Our data provide a strong incentive for the potential use of SGLT2i for the treatment of post-stroke sequelae in T2D.

Brain Swelling versus Infarct Size: A Problematizing Review

In human stroke, brain swelling is an important predictor of neurological outcome and mortality, yet treatments to reduce or prevent brain swelling are extremely limited, due in part to an inadequate understanding of mechanisms. In preclinical studies on cerebroprotection in animal models of stroke, historically, the focus has been on reducing infarct size, and in most studies, a reduction in infarct size has been associated with a corresponding reduction in brain swelling. Unfortunately, such findings on brain swelling have little translational value for treating brain swelling in patients with stroke. This is because, in humans, brain swelling usually becomes evident, either symptomatically or radiologically, days after the infarct size has stabilized, requiring that the prevention or treatment of brain swelling target mechanism(s) that are independent of a reduction in infarct size. In this problematizing review, we highlight the often-neglected concept that brain edema and brain swelling are not simply secondary, correlative phenomena of stroke but distinct pathological entities with unique molecular and cellular mechanisms that are worthy of direct targeting. We outline the advances in approaches for the study of brain swelling that are independent of a reduction in infarct size. Although straightforward, the approaches reviewed in this study have important translational relevance for identifying novel treatment targets for post-ischemic brain swelling.