Endothelial Dysfunction in the Tubule Area Accelerates the Progression of Early Diabetic Kidney Disease.

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. Therefore, understanding the molecular regulatory mechanisms underlying the pathogenesis of DKD is imperative. In this study, we aimed to explore the molecular mechanisms of tubule region endothelial dysfunction in early DKD. Early-stage DKD model was established in 16-week-old female db/db mice for 16 weeks. Body weight, glucose level, and urine albumin-to-creatinine ratio (UACR) were measured. Hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining were performed to evaluate pathological lesions. RNA sequencing data of the kidneys and integrated publicly available single-cell and spatial transcriptome datasets were used to investigate the mechanism of endothelial dysfunction. There was a significant increase in body weight (p = 0.001), glucose levels (p=0.0008), and UACR (p=0.006) in db/db mice compared with db/m mice. H&E and PAS staining showed that vacuolar lesions and protein casts of tubules were the major histopathological changes observed in early-stage DKD mice. The apoptotic pathway in endothelial cells was notably activated in DKD, and Thbs1 was identified as the central gene involved in this apoptotic process. Deconvolution of the cell composition in the RNA sequencing data showed a decrease in the proportion of endothelial cells in the DKD mice. Further analysis of the activity and regulatory network of transcription factors showed that Creb1 was activated in both mouse and human early-stage DKD, suggesting that Creb1 activation may be involved in early kidney injury. The endothelial cell apoptotic pathway is activated in DKD, and the proportion of endothelial cells was reduced in the DKD mice, which is significantly associated with Thbs1. Keywords: Diabetic kidney disease, Endothelial dysfunction, RNA sequencing,Thbs1, Creb1.