Development of a model of renal cell senescence

Chronic kidney disease (CKD) is a major and increasing public health issue affecting more than 10% of the global population. CKD is characterised by a slow, gradual, and irreversible loss of renal functions. Dialysis or transplantation are required in the terminal stages to supplement renal function. Growing evidence suggests that cell senescence plays a crucial role in the pathogenesis of CKD. Indeed, the persistence and accumulation of senescent cells is involved in the development of kidney fibrosis through the secretion of pro-inflammatory and pro-fibrotic factors called senescence-associated secretory phenotype (SASP). In kidneys, senescence-associated alterations seem to affect mostly proximal tubular epithelial cells (PTEC). However, limited information exists to explain the molecular mechanisms underlying these disturbances in renal senescent cells. In this context, our laboratories are studying the emerging roles of senescence in the kidney, and more specifically the underlying metabolic dysfunctions in PTEC. Here, we developed a model of renal senescence in PTEC by exposing human kidney cells (HK-2 cell line) to 300 and 500 µM of hydrogen peroxide (H2O2) for two hours. Three and five days after exposure to H2O2, HK-2 cells exhibited several senescence markers, such as enlarged cell and nuclear sizes, senescence-associated β-galactosidase (SA-β-gal)- and γH2AX-staining, overexpression of IL6, IL8 and CDKN1A (p21) genes, cell cycle arrest and decreased expression of LMNB1 gene (lamin B1). Interestingly, disturbances in lipid metabolism were also measured, notably through the appearance of lipid droplets in senescent cells. This may therefore participate to kidney dysfunction. However, additional investigations in this model of renal senescence are necessary to further characterize the contribution of the disturbance of lipid metabolism in senescence-induced CKD.