SGLT2 inhibitors, hemodynamics, and kidney protection

SGLT2 inhibitors as a potential therapeutic option for pulmonary hypertension: mechanisms and clinical perspectives

Pulmonary arterial hypertension (PAH), one subtype of pulmonary hypertension (PH), is a life-threatening condition characterized by pulmonary arterial remodeling, elevated pulmonary vascular resistance, and blood pressure in the pulmonary arteries, leading to right heart failure and increased mortality. The disease is marked by endothelial dysfunction, vasoconstriction, and vascular remodeling. The role of Sodium-Glucose Co-Transporter-2 (SGLT2) inhibitors, a class of medications originally developed for diabetes management, is increasingly being explored in the context of cardiovascular diseases, including PAH, due to their potential to modulate these pathophysiological processes. In this review, we systematically examine the burgeoning evidence from both basic and clinical studies that describe the effects of SGLT2 inhibitors on cardiovascular health, with a special emphasis on PAH. By delving into the complex interactions between these drugs and the potential pathobiology that underpins PH, this study seeks to uncover the mechanistic underpinnings that could justify the use of SGLT2 inhibitors as a novel therapeutic approach for PAH. We collate findings that illustrate how SGLT2 inhibitors may influence the normal function of pulmonary arteries, possibly alleviating the pathological hallmarks of PAH such as inflammation, oxidative stress, aberrant cellular proliferation, and so on. Our review thereby outlines a potential paradigm shift in PAH management, suggesting that these inhibitors could play a crucial role in modulating the disease's progression by targeting the potential dysfunctions that drive it. This comprehensive synthesis of existing research underscores the imperative need for further clinical trials to validate the efficacy of SGLT2 inhibitors in PAH and to integrate them into the therapeutic agents used against this challenging disease.

SGLT2 inhibitors in peritoneal dialysis: a promising frontier toward improved patient outcomes

Peritoneal dialysis (PD) stands as an important modality among kidney replacement therapies for end-stage kidney disease, offering patients remarkable flexibility and autonomy. Despite its widespread use, challenges such as glucose-related complications, peritoneal membrane fibrosis, declining renal function, and cardiovascular risks persist, necessitating innovative therapeutic approaches. Sodium–glucose cotransporter 2 (SGLT2) inhibitors, originally developed for treating type 2 diabetes mellitus, have recently shown promise as add-on therapy for patients with diabetic and non-diabetic chronic kidney disease (CKD), even in advanced stages. This review describes the potential role of SGLT2 inhibitors as a breakthrough therapeutic option in PD, emphasizing their ability to address unmet clinical needs and improve patient outcomes. The multiple effects of SGLT2 inhibitors in CKD, including metabolic modulation, antihypertensive, diuretic, anemia-reducing, antioxidant, and antiinflammatory properties, are reviewed in the context of PD challenges. Additionally, the potentially protective influence of SGLT2 inhibitors on the integrity of the peritoneal membrane and the transport of solutes and water in the peritoneum are emphasized. Despite these encouraging results, the paper highlights the potential risks associated with SGLT2 inhibitors in PD and emphasizes the need for cautious and thorough investigation of dosing, long-term safety considerations, and patient-specific factors through comprehensive clinical trials. Looking forward, the review argues for well-designed studies to evaluate the expanded safety profile of SGLT2 inhibitors in PD, with particular attention paid to peritoneal membrane integrity and overall patient outcomes.

Intrarenal Mechanisms of Sodium-Glucose Cotransporter-2 Inhibitors on Tubuloglomerular Feedback and Natriuresis

When sodium-glucose cotransporter-2 (SGLT2) inhibitors were first introduced a decade ago, no one expected them to have substantial effects beyond their known glucose-lowering effects, until the emergence of evidence of their robust renal and cardiovascular benefits showing that they could attenuate progression of kidney disease, irrespective of diabetes, as well as prevent the development of acute kidney injury. Still, the precise and elaborate mechanisms underlying the major organ protection of SGLT2 inhibitors remain unclear. SGLT2 inhibitors inhibit the reabsorption of sodium and glucose in the proximal tubule of the kidney and then recovers tubuloglomerular feedback, whereby SGLT2 inhibitors reduce glomerular hyperfiltration. This simple demonstration of their beneficial effects has perplexed experts in seeking more plausible and as yet undisclosed explanations for the whole effects of SGLT2 inhibitors, including metabolism reprogramming and the modulation of hypoxia, inflammation, and oxidative stress. Given that the renal benefits of SGLT2 inhibitors in patients with kidney disease but without diabetes were comparable to those seen in patients with diabetes, it may be reasonable to keep the emphasis on their hemodynamic actions. In this context, the aim of the present review is to provide a comprehensive overview of renal hemodynamics in individuals with diabetes who are treated with SGLT2 inhibitors, with a focus on natriuresis associated with the regulation of tubuloglomerular feedback and potential aquaresis. Throughout the discussion of alterations in renal sodium and water transports, particular attention will be given to the potential enhancement of adenosine and its receptors following SGLT2 inhibition.

Evaluation of renal cold ischemia-reperfusion injury with intravoxel incoherent motion diffusion-weighted imaging and blood oxygenation level-dependent MRI in a rat model

Purpose: Cold ischemia-reperfusion injury (CIRI) is one of the most serious complications following renal transplantation. The current study investigated the feasibility of Intravoxel Incoherent Motion (IVIM) imaging and blood oxygenation level-dependent (BOLD) in the evaluation of different degrees of renal cold ischemia-reperfusion injury in a rat model. Methods: Seventy five rats were randomly divided into three groups (N = 25 for each group): T0: sham-operated group, T2/T4: CIRI groups with different cold ischemia hours (2, 4 h, respectively). The rat model of CIRI group was established by left kidney cold ischemia with right nephrectomy. All the rats received a baseline MRI before the surgery. Five rats in each group were randomly selected to undergo an MRI examination at 1 h, day 1, day 2 and day 5 after CIRI. The IVIM and BOLD parameters were studied in the renal cortex (CO), the outer stripe of the outer medulla (OSOM), and the inner stripe of the outer medulla (ISOM) followed by histological analysis to examine Paller scores, peritubular capillary (PTC) density, apoptosis rate and biochemical indicators to obtain the contents of serum creatinine (Scr), blood urea nitrogen (BUN), superoxide dismutase (SOD) and malondialdehyde (MDA). Results: The D, D*, PF and T2* values in the CIRI groups were lower than those in the sham-operated group at all timepoints (all p < 0.05). The prolonged cold ischemia times resulted in gradually lower D, D*, PF and T2* values (all p < 0.05). The D and T2* values of cortex and OSOM in Group T0 and T2 returned to the baseline level (all p > 0.05) except Group T4. The D* and PF values of cortex, OSOM and ISOM in Group T2 and T4 still remained below the normal levels (all p < 0.05) except Group T0. D, D*, PF and T2* values were strongly correlated with histopathological (Paller scores, PTC density and apoptosis rate) and the biochemistry indicators (SOD and MDA) (|r|>0.6, p < 0.001). D*, PF and T2* values were moderately to poorly correlated with some biochemistry indicators (Scr and BUN) (|r|<0.5, p < 0.05). Conclusion: IVIM and BOLD can serve as noninvasive radiologic markers for monitoring different degrees of renal impairment and recovery after renal CIRI.

Recent advances in molecular mechanisms of acute kidney injury in patients with diabetes mellitus

Several insults can lead to acute kidney injury (AKI) in native kidney and transplant patients, with diabetes critically contributing as pivotal risk factor. High glucose per se can disrupt several signaling pathways within the kidney that, if not restored, can favor the instauration of mechanisms of maladaptive repair, altering kidney homeostasis and proper function. Diabetic kidneys frequently show reduced oxygenation, vascular damage and enhanced inflammatory response, features that increase the kidney vulnerability to hypoxia. Importantly, epidemiologic data shows that previous episodes of AKI increase susceptibility to diabetic kidney disease (DKD), and that patients with DKD and history of AKI have a generally worse prognosis compared to DKD patients without AKI; it is therefore crucial to monitor diabetic patients for AKI. In the present review, we will describe the causes that contribute to increased susceptibility to AKI in diabetes, with focus on the molecular mechanisms that occur during hyperglycemia and how these mechanisms expose the different types of resident renal cells to be more vulnerable to maladaptive repair during AKI (contrast- and drug-induced AKI). Finally, we will review the list of the existing candidate biomarkers of diagnosis and prognosis of AKI in patients with diabetes.

Emerging roles of Sodium-glucose cotransporter 2 inhibitors in Diabetic kidney disease

Diabetic kidney disease (DKD), a severe microvascular complication of diabetes mellitus, is the primary cause of end stage renal disease (ESRD). Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a class of novel anti-diabetic drugs for DKD, which have the potential to prevent renal function from failing. The involved mechanisms have garnered considerable attention. Besides hypoglycemic effect, it seems that various glucose-independent nephroprotective mechanisms also have a role. Among them, improvement in tubuloglomerular feedback is considered as the main reason, followed by reduced intraglomerular pressure and fluid load. In addition, reduced blood pressure, anti-inflammatory effects, nutrient deprivation signaling as well as improved endothelial function are also important. In the future, clinical trials and mechanistic studies might further complement the current knowledge on SGLT2 inhibitors and facilitate to translate these agents to clinical use. Here, we review these mechanisms of SGLT2 inhibitors with an emphasis on kidney protective effects.

A Shared Nephroprotective Mechanism for Renin-Angiotensin-System Inhibitors, Sodium-Glucose Co-Transporter 2 Inhibitors, and Vasopressin Receptor Antagonists: Immunology Meets Hemodynamics

A major paradigm in nephrology states that the loss of filtration function over a long time is driven by a persistent hyperfiltration state of surviving nephrons. This hyperfiltration may derive from circulating immunological factors. However, some clue about the hemodynamic effects of these factors derives from the effects of so-called nephroprotective drugs. Thirty years after the introduction of Renin-Angiotensin-system inhibitors (RASi) into clinical practice, two new families of nephroprotective drugs have been identified: the sodium-glucose cotransporter 2 inhibitors (SGLT2i) and the vasopressin receptor antagonists (VRA). Even though the molecular targets of the three-drug classes are very different, they share the reduction in the glomerular filtration rate (GFR) at the beginning of the therapy, which is usually considered an adverse effect. Therefore, we hypothesize that acute GFR decline is a prerequisite to obtaining nephroprotection with all these drugs. In this study, we reanalyze evidence that RASi, SGLT2i, and VRA reduce the eGFR at the onset of therapy. Afterward, we evaluate whether the extent of eGFR reduction correlates with their long-term efficacy. The results suggest that the extent of initial eGFR decline predicts the nephroprotective efficacy in the long run. Therefore, we propose that RASi, SGLT2i, and VRA delay kidney disease progression by controlling maladaptive glomerular hyperfiltration resulting from circulating immunological factors. Further studies are needed to verify their combined effects.

Empagliflozin Protects against Pulmonary Ischemia/Reperfusion Injury via an Extracellular Signal-Regulated Kinases 1 and 2-Dependent Mechanism

Ischemia/reperfusion (I/R) injury of the lung can lead to extensive pulmonary damage. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are insulin-independent, oral antihyperglycemic agents used for treating type 2 diabetes mellitus (T2DM). Although their cardioprotective properties have been reported, their potential roles in pulmonary protection in vivo are poorly characterized. Here, we tested a hypothesis that empagliflozin, an SGLT2 inhibitor, can protect lungs in a mouse model of lung I/R injury induced by pulmonary hilum ligation in vivo. We assigned C57/BL6 mice to sham-operated, nonempagliflozin-treated control, or empagliflozin-treated groups. Pulmonary I/R injury was induced by 1-hour left hilum ligation followed by 2-hour reperfusion. Using quantitative polymerase chain reaction (q-PCR) and Western blot analysis, we demonstrate that SGLT2 is highly expressed in mouse kidney but is weakly expressed in mouse lung (n = 5-6 per group, P < 0.01 or P < 0.001). Empagliflozin improved respiratory function, attenuated I/R-induced lung edema, lessened structural damage, inhibited apoptosis, and reduced inflammatory cytokine production and protein concentration in bronchoalveolar lavage (BAL) fluid [P < 0.05 or P < 0.001 versus control group (CON)]. In addition, empagliflozin enhanced phosphorylation of pulmonary extracellular signal-regulated kinases 1 and 2 (ERK1/2) post-I/R injury in vivo (P < 0.001, versus CON, n = 5 per group). We further showed that pharmacological inhibition of ERK1/2 activity reversed these beneficial effects of empagliflozin. In conclusion, we showed that empagliflozin exerts strong lung protective effects against pulmonary I/R injury in vivo, at least in part via the ERK1/2-mediated signaling pathway. SIGNIFICANCE STATEMENT: Pulmonary ischemia-reperfusion (I/R) can exacerbate lung injury. Empagliflozin is a new antidiabetic agent for type 2 diabetes mellitus. This study shows that empagliflozin attenuates lung damage after pulmonary I/R injury in vivo. This protective phenomenon was mediated at least in part via the extracellular signal-regulated kinases 1 and 2-mediated signaling pathway. This opens a new avenue of research for sodium-glucose cotransporter-2 inhibitors in the treatment of reperfusion-induced acute pulmonary injury.