Molecular Mechanisms Linking Empagliflozin to Renal Protection in the LLC-PK1 Model of Diabetic Nephropathy

Sodium-Glucose Cotransporter 2 Inhibitors as Potential Antioxidant Therapeutic Agents in Cardiovascular and Renal Diseases

Redox (reduction-oxidation) imbalance is a physiological feature regulated by a well-maintained equilibrium between reactive oxygen species (ROS) and oxidative stress (OS), the defense system of the body (antioxidant enzymes). The redox system comprises regulated levels of ROS in the cells, tissues and the overall organ system. The levels of ROS are synchronized by gradients of electrons that are generated due to sequential reduction and oxidation of various biomolecules by various enzymes. Such redox reactions are present in each cell, irrespective of any tissue or organ. Failure in such coordinated regulation of redox reactions leads to the production of excessive ROS and free radicals. Excessively produced free radicals and oxidative stress affect various cellular and molecular processes required for cell survival and growth, leading to pathophysiological conditions and, ultimately, organ failure. Overproduction of free radicals and oxidative stress are the key factors involved in the onset and progression of pathophysiological conditions associated with various cardiovascular and renal diseases. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) are glucose-lowering drugs prescribed to diabetic patients. Interestingly, apart from their glucose-lowering effect, these drugs exhibit beneficial effects in non-diabetic patients suffering from various cardiovascular and chronic kidney diseases, perhaps due to their antioxidant properties. Recently, it has been demonstrated that SGLT2is exhibit strong antioxidant properties by reducing ROS and OS. Hence, in this review, we aim to present the novel antioxidant role of SGLT2is and their consequent beneficial effects in various cardiovascular and renal disease states.

A novel soluble guanylate cyclase activator, avenciguat, in combination with empagliflozin, protects against renal and hepatic injury in diabetic db/db mice

Diabetic complications are linked to oxidative stress, which hampers the cyclic guanosine monophosphate production by inhibiting nitric oxide/soluble guanylate cyclase (sGC) signaling. This study aimed to determine whether the administration of a novel sGC activator avenciguat alone or in combination with an SGLT2 inhibitor could slow the progression of renal and liver fibrosis in the type 2 diabetic and uninephrectomized db/db mouse model. Experiment groups included normal controls, untreated db/db mice terminated at 12 and 18 wk of age, and db/db mice treated with either one of two doses of avenciguat alone, empagliflozin (Empa) alone, or a combination of both from weeks 12 to 18 of age. Untreated db/db mice exhibited obesity, hyperglycemia, elevated levels of HbA1c and triglycerides (TG), and developed progressive albuminuria, glomerulosclerosis, fatty liver, and liver fibrosis between weeks 12 and 18 of age, accompanied by increased renal and liver production of fibronectin, type-IV collagen, laminin, and increased oxidative stress markers. Avenciguat had no effect on body weight but reduced both blood HbA1c and TG levels, whereas Empa reduced HbA1c but not TG levels as compared with untreated db/db. Both avenciguat and Empa alone effectively slowed the progression of diabetes-associated glomerulosclerosis and liver fibrosis. Importantly, avenciguat, especially at high doses in combination with Empa, further lowered these progression markers compared with baseline measurements. These results suggested that either avenciguat alone or in combination with Empa is therapeutic. Avenciguat in combination with Empa shows promise in halting the progression of diabetic complications.NEW & NOTEWORTHY Whether combining an sGC activator with an SGLT2 inhibitor could better control diabetes-associated oxidative stress and NO-cGMP signal deficiency has not yet been explored. Using the type 2 diabetic db/db mouse model, this study underscores the sGC activator avenciguat as a novel therapy for diabetic nephropathy and liver injury beyond sGLT2 inhibitors. It also highlights the need for further investigation into the combined effects of these two treatments in managing diabetic complications.

Empagliflozin mitigates ponatinib-induced cardiotoxicity by restoring the connexin 43-autophagy pathway

BACKGROUND

Empagliflozin (EMPA), a selective sodium-glucose cotransporter type 2 (SGLT2) inhibitor, has been shown to reduce major adverse cardiovascular events in patients with heart failure of different etiologies, although the underlying mechanism still remains unclear. Ponatinib (PON) is a multi-tyrosine kinase inhibitor successfully used against myeloid leukemia and other human malignancies, but its cardiotoxicity remains worrisome. Cardiac connexins (Cxs) are both substrates and regulators of autophagy and responsible for proper heart function. Alteration in connexin expression and localization have been described in patients with heart failure.

AIMS

To assess whether EMPA can mitigate PON-induced cardiac dysfunction by restoring the connexin 43-autophagy pathway.

METHODS AND RESULTS

Male C57BL/6 mice, randomized into four treatment groups (CNTRL, PON, EMPA, PON+EMPA) for 28 days, showed increased autophagy, decreased Cx43 expression as well as Cx43 lateralization, and attenuated systo-diastolic cardiac dysfunction after treatment with EMPA and PON compared with PON alone. Compared with CNTRL (DMSO), cardiomyocyte-differentiated H9c2 (dH9c2) cells treated with PON showed significantly reduced cell viability to approximately 20 %, decreased autophagy, increased cell senescence and reduced DNA binding activity of serum response factor (SRF) to serum response elements (SRE), which were paralleled by reduction in cardiac actin expression. Moreover, PON induced a significant increase of Cx43 protein and its S368-phosphorylated form (pS368-Cx43), as well as their displacement from the plasma membrane to the perinuclear and nuclear cellular region. All these effects were reverted by EMPA.

CONCLUSION

EMPA attenuates PON-induced cardiotoxicity by reducing senescence, enhancing the SRE-SRF binding and restoring the connexin 43-autophagy pathway. This effect may pave the way to use of SGLT2 inhibitors in attenuating tyrosine-kinase inhibitor cardiotoxicity.

Metabolic effects of SGLT2i and metformin on 3-hydroxybutyric acid and lactate in db/db mice

Combining a Sodium-Glucose-Cotransporter-2-inhibitor (SGLT2i) with metformin is recommended for managing hyperglycemia in patients with type 2 diabetes (T2D) who have cardio-renal complications. Our study aimed to investigate the metabolic effects of SGLT2i and metformin, both individually and synergistically. We treated leptin receptor-deficient (db/db) mice with these drugs for two weeks and conducted metabolite profiling, identifying 861 metabolites across kidney, liver, muscle, fat, and plasma. Using linear regression and mixed-effects models, we identified two SGLT2i-specific metabolites, X-12465 and 3-hydroxybutyric acid (3HBA), a ketone body, across all examined tissues. The levels of 3HBA were significantly higher under SGLT2i monotherapy compared to controls and were attenuated when combined with metformin. We observed similar modulatory effects on metabolites involved in protein catabolism (e.g., branched-chain amino acids) and gluconeogenesis. Moreover, combination therapy significantly raised pipecolate levels, which may enhance mTOR1 activity, while modulating GSK3, a common target of SGLT2i and 3HBA inhibition. The combination therapy also led to significant reductions in body weight and lactate levels, contrasted with monotherapies. Our findings advocate for the combined approach to better manage muscle loss, and the risks of DKA and lactic acidosis, presenting a more effective strategy for T2D treatment.

The intellectual base and global trends in inflammation of diabetic kidney disease: a bibliometric analysis

Diabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). The literature on DKD inflammation research has experienced substantial growth. However, there is a lack of bibliometric analyses. This study aimed to examine the existing research on inflammation in DKD by analyzing articles published in the Web of Science Core Collection (WOSCC) over the past 30 years. We conducted a visualization analysis using several software, including CiteSpace and VOSviewer. We found that the literature on inflammation research in DKD has experienced substantial growth, indicating a rising interest in this developing area of study. In this field, Navarro-Gonzalez, JF is the most frequently cited author, Kidney International is the most frequently cited journal, China had the highest number of publications in the field of DKD inflammation, and Monash University emerged as the institution with the most published research. The research area on inflammation in DKD primarily centers around the investigation of 'Glycation end-products', 'chronic kidney disease', and 'diabetic nephropathy'. The emerging research trends in this field will focus on the 'Gut microbiota', 'NLRP3 inflammasome', 'autophagy', 'pyroptosis', 'sglt2 inhibitor', and 'therapeutic target'. Future research on DKD may focus on further exploring the inflammatory response, identifying specific therapeutic targets, studying biomarkers, investigating stem cell therapy and tissue engineering, and exploring gene therapy and gene editing. In summary, this study examines the main areas of study, frontiers, and trends in DKD inflammation, which have significant implications for future research.

Gliflozins Have an Anti-Inflammatory Effect on Renal Proximal Tubular Epithelial Cells in a Diabetic and Inflammatory Microenvironment In Vitro

Inflammation is intimately involved in the pathogenesis of diabetic kidney disease. Inhibition of SGLT-2 by a specific class of drugs, gliflozins, has been shown to reduce inflammation and attenuate the progression of diabetic nephropathy, in addition to its main effect of inhibiting renal glucose reabsorption. We used highly purified human renal proximal tubular epithelial cells (PTCs) as an in vitro model to study the cellular response to a diabetic (high glucose) and inflammatory (cytokines) microenvironment and the effect of gliflozins. In this context, we investigated the influence of SGLT-2 inhibition by empa- and dapagliflozin (500 nM) on the expression of pro-inflammatory factors (IL-1β, IL-6, TNF-α, MCP-1, and ICAM-1). The results clearly indicate an anti-inflammatory effect of both gliflozins. Although induced expression of the four cytokines was only slightly attenuated, there was a clear effect on the expression of the adhesion molecule ICAM-1, a master regulator of cellular responses in inflammation and injury resolution. The induced expression of ICAM-1 mRNA was significantly reduced by approximately 13.5% by empagliflozin and also showed an inhibitory trend with dapagliflozin. However, induced ICAM-1 protein expression was significantly inhibited from 24.71 ± 1.0 ng/mL to 18.81 ± 3.9 (empagliflozin) and 19.62 ± 2.1 ng/mL (dapagliflozin). In conclusion, an additional anti-inflammatory effect of empa- and dapagliflozin in therapeutically observed concentrations was demonstrated in primary human PTCs in vitro.