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Abstract: TH-PO624

Lysosome: At the Crossroads Between Na+-K+-ATPase and NLRP3 in Hyperuricemia-Induced Renal Tubular Injury

Session Information

Category: Health Maintenance, Nutrition, and Metabolism

  • 1300 Health Maintenance, Nutrition, and Metabolism

Authors

  • Xiao, Jing, Huadong hospital affiliated to Fudan University, Shanghai, China
  • Ye, Zhibin, Huadong hospital affiliated to Fudan University, Shanghai, China
Background

We previously demonstrated the impairment of Na+-K+-ATPase (NKA) and NLPR3 signaling in hyperuricemia (HUA)-induced renal tubular injury and NKA was degraded in lysosomes. Here, we investigated the role of lysosome in NKA and NLRP3 signaling under HUA induce renal tubular injury.

Methods

Proximal tubular epithelial cells (PTECs) were incubated with different concentrations (50 μg/mL~200μg/mL) of UA for different times (6h~48 h), and the expression of NLRP3, lysosomal-associated membrane protein 2 (LAMP2), cathepsin B (CB) and interlukin-1β (IL-1β) were detected. CB inhibitor (Ca-074 methyl ester, Ca-074 Me) 10Μm or hydroxychloroquine (HCQ, 50 μM) was added to PTECs for 2h in advance, with the inhibition of NKA by its α subunit siRNA for 48h with or without the UA stimulation, NLRP3, LAMP2 and CB as well as mitochondrial function were detected. In vivo, SPF SD rats were divided (n=4 in each group) into control, HUA group [oxonic acid (OA) 750 mg/kg/d gavage for 8 weeks]; HCQ group (HCQ, with OA 750mg/kg/d for 8 weeks and HCQ 25 mg/kg/d gavage since the 5th week and for 4 weeks); and febuxostat group (Feb, with OA 750mg/kg/d for 8 weeks and Feb 3 mg/kg/d gavage since the 5th week for 4 weeks). Renal cortex NKA activity, its expression, CB, LAMP2, NLRP3, IL-1β and uncoupling protein 2 (UCP2) were examined.

Results

UA time and dose-dependently increased the expression of LAMP2 and CB. Ca-074 Me or HCQ alleviated the expression of NLRP3, LAMP2 and CB, mitochondrial dysfunction caused by UA and/or NKA siRNA. OA significantly increased serum UA levels in SD rats and developed reduced urinary UA excretion, renal cortex NKA activity and its expression, increased the expression of NLRP3, Il-1β, CB, LAMP2, and UCP2 expressions, compared with control. HCQ, but not Feb treatment, significantly increased urinary UA excretion. HCQ demonstrated similar effects with Feb in enhancing renal cortex NKA activity and expression, reducing the expression of NLRP3, Il-1β, CB, LAMP2, and UCP2 expressions, compared with HUA group.

Conclusion

UA induces lysosomal damage to release lysosomal contents and activate NLRP3 inflammasome. Lysosomal function protection could alleviate NKA-NLRP3 signaling pathway and effectively improve mitochondrial function in vitro and in vivo, suggesting that lysosome function plays an important role in HUA-induced renal tubular epithelial cell injury.