Pharmacological enhancement of circadian clock ameliorated fibrosis in adenine induced chronic kidney disease

초록

Background and Aims Circadian clock regulates diverse biological processes. Recent studies demonstrating the important role of dysregulated molecular clock system in several metabolic diseases as well as in chronic kidney disease (CKD) suggest that modulation of clock machinery might be an attractive therapeutic target. Method We optimized a substance (compound X) that enhances the circadian molecular rhythm and validated its effect in HK-2 cells as well as in mouse model of adenine induced CKD. Results By using transcriptome analysis of whole kidneys, we identified that 19% of CKD associated genes showed rhythmic expressions in circadian manner. Gene enrichment analysis revealed that the rhythmic genes involved in extracellular matrix/collagen/myofibroblasts showed upregulation while those involved in transport/brush border/proximal tubule showed downregulation in CKD. Treatment with compound X in HK-2 cells resulted in marked attenuation of epithelial mesenchymal transition upon transforming growth factor-b (TGF- b) stimulation. Along with these in vitro data, we also observed the preserved kidney function and less interstitial fibrosis in compound X treated CKD mice. The protective effect was associated with suppression of inflammation, cell cycle arrest/cellular senescence as well as restoration of several transporters in proximal tubular cells. Conclusion This is the first study that showed that circadian rhythm might be a novel target for CKD progression by suppressing inflammation/fibrosis and enhancing tubular functions. Unlike other strategies targeting single pathway, targeting circadian rhythm seems to be more promising due to its multi-target effects. A better understanding of the complex role of circadian clock in kidney diseases may provide new perspectives for the prevention and treatment of CKD.