title: Involvement of endoplasmic reticulum stress in angiotensin II-induced NLRP3 inflammasome activation in human renal proximal tubular cells in vitro.
abstract: OBJECTIVE
  NLRP3 inflammasome plays an important role in renal injury and may be a therapeutic target in the treatment of patients with progressive chronic kidney disease. In this study we investigated whether angiotensin II (Ang II)-induced NLRP3 inflammasome activation was linked to endoplasmic reticulum stress (ERS) in human renal proximal tubular cells in vitro.
  
  
  METHODS
  Human kidney proximal epithelial cells (HK-2) were pretreated with telmisartan or 4-PBA, and then treated with Ang II. The expression levels of mRNAs and proteins related to NLRP3 inflammasomes and ERS was examined by real-time PCR, Western blot and immunofluorescence.
  
  
  RESULTS
  Treatment with Ang II (10, 100, and 1000 nmol/L) increased the expression of the inflammasome markers NLRP3 and ASC, as well as caspase-1, IL-1β, and IL-18 in dose- and time-dependent manners with peak levels detected at 100 nmol/L and 12 h. Ang II-induced increases in the expression of NLRP3, ASC, caspase-1, IL-1β, and IL-18 were significantly reduced by pretreatment with telmisartan (1 μmol/L). Immunofluorescence studies showed that Ang II increased the expression of NLRP3 and ASC, which was inhibited by telmisartan. Furthermore, Ang II treatment increased the expression of ERS markers GRP78 and p-eIF2α in dose- and time-dependent manners, which was significantly reduced by telmisartan. Moreover, Ang II-induced increases in the expression of NLRP3, ASC, caspase-1, IL-1β, and IL-18 were significantly inhibited by pretreatment with the ERS inhibitor 4-PBA (5 mmol/L).
  
  
  CONCLUSIONS
  Ang II treatment induces NLRP3 inflammasome activation in HK-2 cells in vitro and ER stress is involved in this process, which may represent a new mechanism for the renal rennin-angiotensin system to induce tubulointerstitial inflammation.
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Lin-li
authors.initials: LL
authors.lastname: Lv
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Ri-ning
authors.initials: RN
authors.lastname: Tang
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Kun-ling
authors.initials: KL
authors.lastname: Ma
authors.affiliation: Institute of Nephrology, Zhongda Hospital, Southeast University School of Medicine, Nanjing 210009, China.
authors.forename: Bi-cheng
authors.initials: BC
authors.lastname: Liu
mesh_terms: D000804:Angiotensin II / Q000633:toxicity*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein
chemical_list: D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D000804:Angiotensin II