Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis

SGLT2 inhibitor empagliflozin ameliorates tubulointerstitial fibrosis in DKD by downregulating renal tubular PKM2

BACKGROUND AND OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to prevent the progression of diabetic kidney disease (DKD). However, their impact on renal fibrosis remains largely uninvestigated. This study aimed to explore the effect of SGLT2 inhibitor empagliflozin on renal fibrosis in DKD patients and DKD models, and the molecular mechanisms involved.

METHODS

Kidney samples of DKD patients and DKD models were used in this study. DKD mouse models included STZ-treated CD-1 mice and HFD-fed C57BL/6 mice were all treated with empagliflozin for 6 to 12 weeks. Kidney pathological changes were analysed and fibrotic factors were detected. HK-2 cells were treated with normal glucose (NG), high glucose (HG), or HG with empagliflozin. RNA sequencing was employed to identify the differentially expressed genes. Epithelial-mesenchymal transition (EMT) markers were detected. Binding of transcription factor and target gene was determined using a dual-luciferase reporter assay.

RESULTS

Empagliflozin significantly ameliorated kidney fibrosis in DKD patients and DKD models. This was evidenced by tubulointerstitial fibrosis reduction observed through PAS and Masson staining, along with fibrotic factors downregulation. RNA sequencing and the subsequent in vitro and in vivo validation identified PKM2 as the most significantly upregulated glycolytic enzyme in DKD patients and models. Empagliflozin downregulated PKM2 and alleviated EMT and renal fibrosis. Importantly, empagliflozin improves fibrosis by downregulating PKM2. The downregulation of PKM2 by empagliflozin was achieved by inhibiting the binding of estrogen-related receptor α at the promoter.

CONCLUSIONS

Empagliflozin ameliorates kidney fibrosis via downregulating PKM2 in DKD.

The role and mechanism of m6A methylation in diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus, characterized by progressive deterioration of renal structure and function, which may eventually lead to end-stage kidney disease (ESKD). The N6-methyladenosine (m6A) methylation, an important modality of RNA modification, involves three classes of key regulators, writers (e.g., METTL3), erasers (e.g., FTO, ALKBH5) and readers (e.g., YTHDF2), which play important roles in DN. Writers are responsible for introducing m6A modifications on RNAs, erasers remove m6A modifications and readers recognize and bind m6A-modified RNAs to regulate RNAs functions, such as mRNA stability, translation and localization. In DN, abnormal m6A modification may promote kidney injury and proteinuria by regulating key pathways involved in multiple processes, including lipid metabolism and inflammatory response, in kidney cells such as podocytes. Therefore, an in-depth study of the role and mechanism of m6A methylation that are regulated by "writers", "erasers" and "readers" in DN is expected to provide new targets and strategies for the prevention and treatment of DN.

Mesenchymal Stem Cell Therapy: Therapeutic Opportunities and Challenges for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD), which severely affects the quality of patients' lives. However, the current therapeutic approaches can only postpone its progression to ESRD. It is therefore imperative to develop a novel therapeutic strategy for renal injury in DKD, with the objective of restoring renal function and reversing the process of ESRD. In recent years, the potential of mesenchymal stem cell (MSC) therapy for DKD has garnered increasing attention within the scientific community. Preclinical research on MSC therapy has yielded promising results, and the safety of MSC treatment in vivo has been substantiated in clinical studies. An increasing body of evidence suggests that MSC therapy has significant potential for the treatment of DKD. This article reviews the existing research on MSCs and their derived exosomes in treating DKD and analyzes the underlying mechanism of MSC-based therapy for DKD. Additionally, we discuss the potential of combining MSC therapy with conventional pharmacological treatments, along with the constraints and prospects of MSC therapy for DKD. We hope this review can provide a precise and comprehensive understanding of MSCs for the treatment of DKD.

N6-methyladenine RNA methylation epigenetic modification and diabetic microvascular complications

N6-methyladensine (m6A) has been identified as the best-characterized and the most abundant mRNA modification in eukaryotes. It can be dynamically regulated, removed, and recognized by its specific cellular components (respectively called "writers," "erasers," "readers") and have become a hot research field in a variety of biological processes and diseases. Currently, the underlying molecular mechanisms of m6A epigenetic modification in diabetes mellitus (DM) and diabetic microvascular complications have not been extensively clarified. In this review, we focus on the effects and possible mechanisms of m6A as possible potential biomarkers and therapeutic targets in the treatment of DM and diabetic microvascular complications.