ABSTRACT
Objective To observe the regulation of Toll-like receptor 4 (TLR4) signal and the release of inflammation factors after angiotensin Ⅱ (Ang Ⅱ) stimulation in rat mesangial cells under high glucose condition,revealing the innate immune-related mechanism of injury by Ang Ⅱ on mesangial cells under high glucose.Methods After synchronization,cells incubated with Ang Ⅱ (10-7 mmo/L) and/or high glucose (25 mmol/L) were used as the stimulation group,cells without stimulation were as normal control (5.6 mmol/L glucose).To determine the role of TLR4 and the adaptor myeloid differentiation factor 88 (MyD88),equal number of HBZY-1 cells were added with 10-5 mmol/L irbesartan and/or TLR4 blocker (10 mg/L) for 1 h and then incubated with Ang Ⅱ (10-7 mmo/L) and/or high glucose (25 mmol/L) for 12 h or 24 h respectively.Real-time PCR was used to analyze TLR4 mRNA and MyD88 mRNA expression after 12 h.Immunofluorescence was used to observe TLR4 protein expression after 24 h; Western blotting was used to observe TLR4,MyD88 and nuclear factor κB (NF-κB) protein; ELISA was used to detect the concentration of MCP-1,IL-6 in cell supernatant respectively.Results Compared with normal control group,TLR4 mRNA and MyD88 mRNA were highly expressed in high glucose or Ang Ⅱ-induced HBZY-1 cells (P ＜ 0.01),TLR4,MyD88 and NF-κB protein as well as MCP-1,IL-6 were also up-regulated significantly (P ＜ 0.01).Compared with high glucose or Ang Ⅱ group,MyD88 and NF-κB protein as well as MCP-1,IL-6 were further up-regulated markedly in Ang Ⅱ and high glucose costimulated group (P ＜ 0.01).In HBZY-1 cells that were preincubated with irbesartan and/or TLR4 blocker,TLR4 and MyD88 protein expression were obviously inhibited,IL-6 and MCP-1 production were also decreased remarkably compared with high glucose and/or Ang Ⅱ group (P ＜ 0.01).Conclusions High glucose and Ang Ⅱ stimulate the release of proinflammatory factors in rat glomerular mesangial cells via TLR4-MyD88 pathway.This process is inhibited by irbesartan or TLR4 blocker via modulation of the signal.Ang Ⅱ has the positive-regulation potential on the release of inflammation factors via TLR4 signal in rat mesangial cells under high glucose condition.
ABSTRACT
Objective To observe the expression of toll like receptor 4(TLR4) Signaling and the release of inflammation factors in rat tubular epithelial cell(NRK-52E) under high glucose condition after TLR4-siRNA transfection.Methods Three TLR4-siRNA sequences were designed and synthesized.The transfection efficiency was observed by fluorescence microscope after transfection,and the expression of TLR4 mRNA was detected by real time PCR.The most effective siRNA was selected to be used for forward experiments.After transfection for 24 h,cells were stimulated with 25 mmol/L glucose and/or 10-7 mmol/L Angiotension Ⅱ (Ang Ⅱ) for 12 h,24 h; cells without stimulation were as normal control.Real-time PCR was used to analyze TLR4 and myeloid differentiation factor 88 (MyD88) mRNA expression; Western blot was used to observe TLR4/MyD88 and NF-κB protein expression.ELISA assay was used to detect the concentration of monocyte chemoattractant protein-1 (MCP-1),interleukin-6(IL-6) in cell supernatant after cells were stimulated for 24 h.Results TLR4/ MyD88 mRNA and TLR4/MyD88/NF-κB protein were highly expressed under high glucose or Ang Ⅱ co -incubated NRK-52E(P ＜ 0.01),the MCP-1 and IL-6 levels were also increased markedly compared with normal control group (P ＜ 0.01).TLR4/MyD88 mRNA and TLR4/MyD88/NF-kB protein expressions were obviously inhibited in cells that were transfected with TLR4-siRNA compared with high glucose group(P ＜ 0.01),MCP-1 and IL-6 production decreased remarkably compared with high glucose or Ang Ⅱ co-stimulated group(P ＜ 0.01).Conclusions High glucose can lead to the activation of TLR4/ MyD88/NF-kB signaling and the secretion of inflammation factors in NRK-52E,Ang Ⅱ further augments these effects.The effect can be blocked efficiently by specific siRNA gene silence.TLR4 signaling plays a pivotal role in the innate-immune inflammatory reaction in NRK-52E.
ABSTRACT
ObjectiveTostudytheroleof hotshockprotein (HSP)47in tubulointerstitial fibrosis induced by transforming growth factor β1(TGF-β1),and to explore its possible mechanism.Methods Human proximal tubular epithelial cells(HK-2) were divided into threegroups:control,TGF-β1andHSP47siRNA. Theexpressionsof HSP47, collagenⅣ,fibronectin(FN),plasminogen activator inhibitor 1(PAI-1) mRNA and HSP47,collagen Ⅳ,FN protein were detected by RT-PCR and Western blotting respectively.PAl-1 protein was detected by ELISA. ResultsHK-2expressedHSP47innormalmedium. ThemRNAandprotein expressions of HSP47 up-regulated in concentration- and time-dependent manner in HK-2 cells induced with increasing concentrations of TGF-β1(0,2.5,5,10 μg/L) and with prolong times (12,24,48 h),and peaked at 10 μg/L TGF-β1 for 48 h.Similar phenomena was observed in the mRNA andproteinexpressionsof collagenⅣ, FN, PAI-1inHK-2 cellsinducedbyincreasing concentrations of TGF-β1 (0,2.5,5,10 μg/L) at different time points (12,24,48 h),and peaked at 10 μg/L TGF-β1 for 48 h.HSP47 siRNA could significantly reduce the up-regulation of mRNA and protein expressions of HSP47,collagen Ⅳ,FN,PAI-1 in HK-2 cells induced by TGF-β1.Conclusion HSP47 can promote renal tubulointerstitial fibrosis maybe through the regulation of the expressions of collagen Ⅳ,FN,PAI-1.
ABSTRACT
Objective To observe the release of inflammation-related factors after angiotensin Ⅱ (Ang Ⅱ ) stimulation in rat tubular epithelial cells (NRK-52E), to analyze whether these effects were mediated by TLR4-MyD88 pathway, and to reveal the novel mechanism of injury by Ang Ⅱ on NRK-52E cells. Methods After synchronization, cells incubated with AngⅡ (10-7 mmol/L) were used as the stimulation group, cells without stimulation were as normal control. To determine the role of TLR4 and the adaptor MyD88, equal number of NRK-52E cells was added with 10-5 mmol/L candesartan or 20 mg/L TLR4 blocking peptide for 1 h and then incubated with Ang Ⅱ (10-7 mmol/L) respectively. RT-PCR was used to analyze TLR4 mRNA and MyD88 mRNA expression. Immunofluorescence and confocal microscopy were used to observe TLR4 protein expression. ELISA was used to detect the concentration of tumor necrosis factor-alpha (TNF-α) and heat shock protein 47(HSP47) in cell supernatant respectively. Results TLR4 and MyD88 were highly expressed in Ang Ⅱ-induced NRK-52E cells (P＜0.01), and the TNF-α and HSP47 levels were also increased markedly compared with control group (P＜0.01). In NRK-52E cells that were pre-incubated with candesartan, TLR4 and MyD88 expression were obviously inhibited,subsequently, HSP47 and TNF-α production decreased remarkably compared with Ang Ⅱ group (P＜0.01). TLR4 blocking peptide had the similar effect in a dose-dependent manner, in which its effect was dependent on inhibiting TLR4-MyD88 expression. Conclusion The mechanism of Ang Ⅱ -induced injury effect on NRK-52E cells is related to the increase of TLR4-MyD88 activity,which is followed by the enhance of TNF-α and HSP47 expression. This process is inhibited by candesartan via modulation of innate immune pathway.