#4825 AUTOPHAGY REGULATES TUBULAR CELL SENESCENCE IN DIABETIC KIDNEY DISEASE

Abstract

Abstract Background and Aims Cellular senescence commonly occurs in innate renal cells of diabetic kidney disease (DKD) and autophagy may be implicated. However, the characteristics of senescent cells in different pathological stages of DKD, and the driving force behind the cell senescence remain primarily unknown. This study aimed to examine kidney cellular senescence and its relationship to renal function in DKD and the effect of autophagy on high-glucose-induced cellular senescence. Method According to the DKD pathologic type, 46 patients diagnosed with renal biopsy were categorized into I IIa IIb III IV classes. The other four normal kidney specimens taken from patients with renal trauma were as the control group. Pathological changes in kidney tissues were detected by PAS staining, and the expressions of autophagy-related protein LC3 and senescence marker p21 were demonstrated by immunohistochemical staining. DKD rats were established by intraperitoneal injection with streptozotocin (STZ). HK-2 cells were cultured with 35mM glucose with or without autophagy inhibitor (3-methyladenine, 3-MA) and lysosomal inhibitor (chloroquine CQ). Immunohistochemistry and Western Blot were used to detect the expression of the senescence markers p53 and p21, as well as the autophagy-related proteins LC3 and p62. The electron microscopy technique was used to observe the number of autophagosomes in the DKD rats and each group of HK-2 cells. Results (1) In renal tissues of DKD patients, p21 infiltrated the interstitium and tubules, while LC3 was primarily expressed in the tubules. Both p21 and LC3 expression increased over time as the disease progressed (P<0.05) and were directly proportional to blood creatinine and proteinuria, respectively. Additionally, p21 and LC3 expression were positively correlated. (2) Compared with the control group, the renal tissue of DKD rats displayed higher levels of p21, p53, LC3, and p62 expression (P < 0.05), higher levels of renal tubular autophagosomes, and increased co-expression of p21 and LC3 (P< 0.05). (3) HK-2 cells treated with high glucose exhibited increased expression of p21, p53, p62 and LC3, as well as the number of autophagosomes (P<0.05). (4) 3-MA reduced p21 and p53 expression compared to the high glucose group (P< 0.05), whereas the opposite trend was observed in the CQ treatment (P<0.05). Conclusion Renal tubular cell senescence is closely associated with DKD progression. Autophagic flow may be involved in high glucose-induced renal tubular cell senescence.