title: Soluble monosodium urate, but not its crystal, induces toll like receptor 4-dependent immune activation in renal mesangial cells.
abstract: BACKGROUND
  Uric acid has emerged as a novel and potential modifiable risk factor for the incidence and progression of kidney diseases, however, the deteriorate effect of uric acid on renal mesangial cells remains unclear. The present study is to examine the immune activation of soluble and crystal forms of uric acid in human mesangial cells.
  
  
  METHODS
  We stimulated primary human mesangial cells (HMCs) with increasing concentrations (from 50 to 200 μg/ml) of soluble monosodium urate (MSU) or MSU crystals. We examined interleukin (IL)-1β protein expression levels in cell culture by ELISA. The stimulated HMCs were further stimulated with soluble MSU or MSU crystals at 200 μg/ml with or without the pre-incubation of toll like receptor (TLR) 4 inhibitor TAK242 (1μM). TLR4, nod-like receptor protein (NLRP3, also known as NALP3), IL-1β, human leukocyte antigen (HLA)-DR and CD40 were examined by Realtime-PCR, Western blot and ELISA, respectively.
  
  
  RESULTS
  We found that both soluble MSU and MSU crystals increased IL-1β protein expression levels in dose-dependent fashion. Soluble MSU significantly enhanced the expression of TLR4, NLRP3, IL-1β, HLA-DR and CD40 while MSU crystals only upregulated the expression of TLR4 and IL-1β. TLR4 inhibitor TAK242 significantly blocked the up-regulation of NLRP3, IL-1β, HLA-DR and CD40 induced by soluble MSU while no TAK242 suppression effect on MSU crystals induced IL-1β up-regulation was found.
  
  
  CONCLUSIONS
  Our results suggested that soluble MSU, but not MSU crystals, induce NLRP3, IL-1β, HLA-DR and CD40 upregulation in a TLR4-dependent manner. These findings indicate that soluble MSU may play a pathological role in hyperuricemia induced renal mesangial injury.
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Chensheng
authors.initials: C
authors.lastname: Fu
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Dingyu
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Weijun
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Nephrology, Huadong Hospital affiliated to Fudan University, Shanghai, PR China. Electronic address: yezb2013@163.com.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Ye
mesh_terms: D019013:CD40 Antigens / Q000819:agonists* / Q000235:genetics / Q000276:immunology; D002352:Carrier Proteins / Q000819:agonists* / Q000235:genetics / Q000276:immunology; D003460:Crystallization; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology; D006801:Humans; D053583:Interleukin-1beta / Q000819:agonists* / Q000235:genetics / Q000276:immunology; D050527:Mesangial Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D061251:Primary Cell Culture; D015398:Signal Transduction; D012995:Solubility; D013449:Sulfonamides / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology; D014527:Uric Acid / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D019013:CD40 Antigens; D002352:Carrier Proteins; D006684:HLA-DR Antigens; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D013449:Sulfonamides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C507035:ethyl 6-(N-(2-chloro-4-fluorophenyl)sulfamoyl)cyclohex-1-ene-1-carboxylate; D014527:Uric Acid
keywords: Human renal mesangial cells; Immune activation; Monosodium urate crystal; Soluble monosodium urate; Toll like receptor 4