ABSTRACT
Objective To investigate the effects of angiotensin Ⅱ (Ang Ⅱ) or high glucose on the toll-like receptor 4 (TLR4) expression,inflammatory cytokines and fibrotic factors in human tubular epithelial cells (HK-2),revealing the innate immune-related pathogenesis of diabetic nephropathy (DN) which may have clinical implications.Methods Three TLR4 siRNA sequences were designed and synthetized.After transfection,the most effective siRNA was selected to use for further expriments.The experiment consisted of 2 parts.Part 1:Cells were divided into three groups:normal-glucose group (NG,5.5mmol/L glucose),mannose group (M,5.5 mmol/L glucose + 19.5 mmol/L mannose),High-glucose group (HG,25 mmol/L glucose),preliminary validated the effects of high glucose and high osmotic pressure.Part 2:Cells were divided into seven groups:NG group,HG group,Ang Ⅱ group,Ang Ⅱ + negative group,HG+ negative group,Ang Ⅱ + siRNA group and HG+ siRNA group.Real time PCR was used to analyze the mRNA expression of TLR4,myeloid differentiation factor 88 (MyD88),heat shock protein 47 (HSP47).Western blotting was used to observe the protein expression of TLR4,MyD88,HSP47,NF-κB,type Ⅳ collagen (ColⅣ).ELISA was used to detect the expression of monocyte chemotactic protein-1 (MCP-1) and interleukin-6 (IL-6).Results Compared with NG group,TLR4,MyD88,HSP47 mRNA and TLR4,MyD88,NF-κB,ColⅣ,HSP47 protein were highly expressed under high glucose or Ang Ⅱconditions (P ＜ 0.01),and the expression levels of MCP-1 and IL-6 also increased significantly (P ＜ 0.01).Compared with HG or Ang Ⅱ group,the above indicators were obviously inhibited in the TLR4 siRNA groups (P＜0.01).Comparison between blank vector transfected groups and HG group as well as Ang Ⅱ group indicated no statistic significance (P ＞ 0.05).Conclusions Both Ang Ⅱ and high glucose stimulate TLR4 expression,which result in the up-regulation of inflammatory and fibrotic factors in HK-2.Specific target of TLR4 gene silencing can block the TLR4 pathway that is activated by high glucose and Ang Ⅱ,and thus reduce the inflammatory and fibtogenic factors' release.TLR4 signal is the common innate immune response pathway which induces the release of inflammatory and fibrotic factors in HK-2 under high glucose or high angiotension conditions.
ABSTRACT
Objective To investigate the effete of chitosan on rabbit carotid artery internal jugular vein fistula intimal hyperplasia and its regulation on TLR4/NF-κB signaling.Methods A total of 28 New Zealand white rabbits were randomly divided into the control group(n=4),the model group(n=12) and the chitosan group(n=12).Model group and chitosan group rabbits were established respectively carotid artery internal jugular vein fistula models.After AVF surgery,chitosan was smeared on venous blood vessels and anastomosis.After 4,6 and 8 weeks,the rabbits were separately sacrificed and the AVF venous vascular tissues were taken.The pathological changes of AVF venous vascular tissue in each group were observed.The changes of α-SMA were detected by immunohistochemistry method.The mRNA expressions of PCNA and TLR4 in the tissues were measured by Real-time PCR.At the same time,the protein expressions of PCNA,TLR4,MyD88 and NF-κB were detected by Western blotting.The experimental data were processed by two-factor analysis of variance in statistics.Results (1) After 4 weeks,vascular intimal was thicked in mdel group.In intimal hyperplasia,α-SMA was staining,and then proliferation of vascular smooth muscle cell was significant.As time increasing,more intimal hyperplasia shown obviously,the expression of α-SMA significantly increased.Compared with model group,chitosan group significantly reduced the degree of intimal hyperplasia,the level of α-SMA was significantly decreased,vascular smooth muscle cell proliferation was also extraordinarily decreased.(2) Compared with control group,the expression levels of PCNA,TLR4,MyD88 and NF-κB increased with time.The indices of Chitosan group were markedly higher than control group,but significantly lower than model groups.Conclusion Chitosan can inhibit the proliferation of rabbit VSMCs.The mechanism may be concerned in down regulating TLR4-mediated signaling pathway,reducing the possibility of intimal hyperplasia of rabbit AVF venous blood vessels.
ABSTRACT
Objective To explore the effect of chitosan on vascular smooth muscle cells inhibited proliferation from rabbit arteriovenous fistula and its mechanisms.Methods Established rabbit fistula model on carotid arteryinternal jugular vein.After 1 month cultured VSMCs with primary culture by tissue-pieces inoculation.Cultured VSMCs were divided into three groups:①normal control group.②FBS-treated group:cell were treated with 5％,10％,20％ for 48 h,respectively; established the model of rabbit VSMCs proliferation.③chitosan-treated group:VSMCs cultured with 20％ FBS were exposed to different doses of chitosan(10,100,500,1000,2000μg/ml) for 48 h.And VSMCs were treated for different time (0,12,24,48 h) with Chitosan 1000 μg/ml.Expression levels of PCNA and TLR4/ NF-κB were detected by Western blotting.RT-PCR were applied to measure the mRNA expression of PCNA and TLR4.The protein levels of TLR4 and NF-κB were detected by immunofluorescence.Results Compared with low concentration serum group,FBS-treated VSMCs exhibited a increase in mRNA and protein expression of PCNA and TLR4.FBS-induced protein expression of PCNA and TLR4/NF-κB were reduced by chitosan.Also mRNA expression of PCNA and TLR4 were reduced.They were dependent on concentration and time.In rabbit VSMCs TLR4 was mainly expressed in the cytoplasm and NF-κB expressed mainly in the nucleus.Compared with normal control group,TLR4 and NF-κB protein expression were significantly decreased by chitosan.Conclusion High concentration serum induced VSMCs proliferation.Chitosan can inhibit the proliferation of rabbit VSMCs.It is speculated that the mechanism may be related to the expression of TLR4 receptor activation,reducing expression of downstream factor MyD88 and NF-κB.It is suggest that chitosan can become potential new drugs of arteriovenous fistula prevention of intimal hyperplasia.