Rationale: Extracellular matrix (ECM) remodeling, a key pathological feature in diabetic cardiomyopathy (DCM), is triggered by oxidative stress, inflammation, and various metabolic disorders in the heart. Cardiac fibroblasts (CFs) are the primary source of ECM proteins and the ultimate effector cells in ECM remodeling. CFs are turned on and differentiated into myofibroblasts in response to profibrotic signaling. Rnd3 is a small Rho-GTPase involved in the regulation of cell-cycle distribution, cell migration, and cell morphogenesis. Emerging evidence suggests a link between Rnd3 expression and onset of cardiovascular diseases. However, the role of Rnd3 in DCM remains unknown. Methods: Flow cytometry was employed to separate different types of cardiac cells. Type 2 diabetes mellitus was established in Rnd3 fibroblast-specific knockout and transgenic mice. RNA sequencing and chromatin immunoprecipitation assay were used to discern signaling pathways involved. Results: Rnd3 expression was reduced in cardiac tissues of diabetic mice, with CFs being the primary cell type. Fibroblast-specific upregulation of Rnd3 in vivo was protective against DCM, whereas Rnd3 downregulation in fibroblasts accentuated cardiac oxidative stress, fibrosis, ventricular remodeling, and dysfunction. Moreover, in vitro Rnd3 overexpression significantly attenuated reactive oxygen species production, CF migration and proliferation under high levels of glucose (35 mmol/L) and palmitic acid (500 µmol/L) challenge. Furthermore, RNA sequencing indicated that Notch and TGF-β signaling were significantly suppressed upon Rnd3 overexpression. Mechanistically, Rnd3 regulated Notch and TGF-β signaling by interacting with NICD and ROCK1, respectively. Specifically, glucotoxicity and lipotoxicity control Rnd3 expression by regulating the binding of Nr1H2 and Rnd3 promoter. Conclusions: Our findings provide compelling evidence in that fibroblast-specific activation of Rnd3 protects against cardiac remodeling in DCM, indicating promises of targeting Rnd3 in the treatment of DCM.

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AimsWe aimed to examine efficacy and safety outcomes of sodium-glucose cotransporter-2 inhibitor (SGLT2i) for the treatment of heart failure (HF), especially in patients with heart failure with preserved ejection fraction (HFpEF). Methods and resultsPubMed, Web of Science, and Cochrane Library were searched to identify randomized controlled trials comparing SGLT2i vs. placebo in HF patients. A total of 10 studies with 23 852 HF patients were eventually included. Compared with placebo, SGLT2i is associated with a lower incidence of composite of first hospitalization for heart failure (HHF) or cardiovascular death (CV death) [hazard ratio (HR) = 0.76 95% confidence interval (CI) = 0.71-0.81], which is consistent regardless of the diabetes status, type of gliflozines used, and follow-up duration. SGLT2i can reduce the risk of total HHF or CV death (HR = 0.74, 95%CI = 0.68-0.81), first HHF (HR = 0.69, 95%CI = 0.64-0.75), CV death (HR = 0.88, 95%CI = 0.80-0.96), any death (HR = 0.90, 95%CI = 0.83-0.97), and any serious events (HR = 0.90, 95%CI = 0.87-0.93) in HF patients, at the cost of increased risk of urinary tract infections (risk ratio = 1.17, 95%CI = 1.03-1.33). In HFpEF patients, SGLT2i is associated with a significant reduction of composite of first HHF or CV death (HR = 0.81, 95%CI = 0.73-0.91), first HHF (HR = 0.71, 95%CI = 0.62-0.82), and total HHF or CV death (HR = 0.61, 95%CI = 0.43-0.86). Conclusions Sodium-glucose cotransporter-2 inhibitor contributed to better efficacy outcomes in overall HF patients and showed an inspiring breakthrough in the treatment of HFpEF.