Project description:Introduction: Aging is associated with progressive loss of renal function and vascular structure, with and without chronic kidney disease. However, the mechanisms driving renal vascular aging and potential therapeutic interventions remain poorly understood. Methods: To model this state-of-affairs, we used African turquoise killifish (Nothobranchius furzeri), a naturally short-lived vertebrate. We then inhibited the sodium-glucose co-transporter 2 inhibition (SGLT2i) to test a potential therapeutic intervention. Histological, immunofluorescent, and 3D vascular imaging were used to evaluate glomerular, tubular, and vascular changes. Single-nuclei transcriptomic profiling was performed on whole kidneys to identify age- and treatment-associated molecular signatures. Results: Aged killifish kidneys exhibited hallmark features of human renal aging, including glomerulosclerosis, tubular fibrosis, and vascular rarefaction. Functional changes included increased proteinuria and altered tubular transporter expression. Transcriptomic profiling revealed a metabolic shift from oxidative phosphorylation to glycolysis and upregulation of pro-inflammatory pathways. Aged vasculature also displayed a marked reduction in tight junctions and cell–cell contacts. Dapagliflozin attenuated age-related vascular rarefaction, preserved functional peritubular capillary networks, and reduced albuminuria by restoring a youthful transcriptional profile and enhancing intercellular signaling. However, fish lifespan was not extended. Conclusion: This study establishes the killifish as a translational model for investigating renal vascular aging. We show that SGLT2i preserves renal microvascular structure and function, reduces proteinuria, and reprograms the aged transcriptome. These results support a vascular-protective role of SGLT2i in mitigating age-related renal deterioration.
Project description:The specific mechanism of sodium-glucose cotransporter 2 (SGLT2) inhibitor in heart failure (HF) needs to be elucidated. In this study, we use SGLT2 global knockout (SGLT2-KO) mice to assess the mechanism of SGLT2 inhibitor on HF. Dapagliflozin ameliorates both myocardial infarction (MI)-and transverse aortic constriction (TAC) -induced HF. Global SGLT2-deficiency doesn’t exert protection against adverse remodeling in both MI- and TAC-induced HF models. Dapagliflozin blurs MI- and TAC-induced HF phenotypes in SGLT2-KO mice. Dapagliflozin causes major changes in cardiac fibrosis and inflammation. Based on single-cell RNA sequencing dapagliflozin causes significant differences in the gene expression profile of macrophages and fibroblasts. Moreover, dapagliflozin directly inhibites macrophage inflammation, thereby suppressing cardiac fibroblasts activation. The cardio-protection of dapagliflozin is blurred in mice treated with a C-C chemokine receptor type 2 (CCR2) antagonist. Taken together the protective effects of dapagliflozin against HF are independent of SGLT2, macrophage inhibition is the main target of dapagliflozin against HF.
Project description:The CANVAS program revealed that the SGLT2 inhibitor canagliflozin increases the risk for lower-limb (minor) amputations in type 2 diabetics about a two-fold. On the contrary, the large RCTs with empagliflozin and dapagliflozin did not demonstrate a similar observation. Thus, a question arises whether the increased risk for minor amputations is associated only with canagliflozin or whether it is a class effect of SGLT2 inhibitors. Vascular disorders including defective angiogenesis are among the leading causes of lower-limb amputations. Therefore, here we examined the effects of empagliflozin, dapagliflozin, and canagliflozin on angiogenesis using zebrafish embryos and HUVECs.
Project description:To investigate whether MEK1/2 inhibition attenuates MAPK signaling in RIT1 M90I mice and ameliorates cardiac tissue overgrowth, we treated a cohort of 4-week-old mice harboring a germline Rit1M90I variant with the allosteric MEK1/2 inhibitor trametinib (MEKi).
Project description:Brown adipose tissue (BAT) is a highly vascularized organ with abundant mitochondria that produce heat through uncoupled respiration. Obesity is associated with a reduction of BAT function; however, it is unknown how obesity promotes dysfunctional BAT. Here, using a murine model of diet-induced obesity, we determined that obesity causes capillary rarefaction and functional hypoxia in BAT, leading to a BAT “whitening” phenotype that is characterized by mitochondrial dysfunction, lipid droplet accumulation, and decreased expression of Vegfa. Targeted deletion of Vegfa in adipose tissue of nonobese mice resulted in BAT whitening, supporting a role for decreased vascularity in obesity-associated BAT. Conversely, introduction of VEGF-A specifically into BAT of obese mice restored vascularity, ameliorated brown adipocyte dysfunction, and improved insulin sensitivity. The capillary rarefaction in BAT that was brought about by obesity or Vegfa ablation diminished β-adrenergic signaling, increased mitochondrial ROS production, and promoted mitophagy. These data indicate that overnutrition leads to the development of a hypoxic state in BAT, causing it to whiten through mitochondrial dysfunction and loss. Furthermore, these results link obesity-associated BAT whitening to impaired systemic glucose metabolism.