The Expression And Significance Of Tissue Transglutaminase At The Stage Of Tubulointerstitium Lesions In Kidney From UUO Young Rats

BackgroundRenal fibrosis is the final common pathway of most progressive renal diseases,and also is the pathological basic orpathology characteristics that is leading to chronic renal failure. Therefore it is significant to explore the trigger factors and the relevant mechanisms of tubulointerstitial fibrosis and seek the early reversible factor or treatment.Transforming growth factor beta one is viewed as the prominent fibrosis-promoting molecule and is also appears to play a major role in the pathogenesis of renal fibrosis.More recently,a role has been described for TGF-β1 in the modulation of another key ECM-modulating enzyme:tissue transglutaminase (tTG).Tissue transglutaminase is a calcium-dependent enzyme that catalyzes the cross-linking of polypeptide chains,including those of extracellular matrix(ECM) proteins,through the formation ofε-(γ-glutamyl) lysine bonds.This crosslinking leads to the formation of protein polymers that are highly resistant to degradation.As a consequence,the enzyme has been implicated in the deposition of ECM protein in renal fibrotic diseases.ObjectiveTo observe the trend,relevance and potential Pathologic significance of tissue transglutaminase (tTG) and transforming growth factor-β1(TGF-β1) in the course of tubulointerstitial lesions in kidneys of young rats with unilateral ureteral obstraction(UUO),and the interfering effects of the treatment with benazepril and losartan.MethodsYoung wistar male rats with unilateral ureteral obstruction(UUO) were served as experiment models.All of the rats were randomly divided into three groups,which were untreated group after UUO(UUO group,n=32),treated group after UUO(UUO+ACEI+ARB group,n=32),and sham operation group(control group,n=32).At the time points --day 3,7,14, 28,eight rats were sacrificed in each group and the left renal tissues were obtained to evaluate the renal tissues morphologic changes through HE and Masson staining,at the same time,we detected the protein expression of tTG,TGF-β1,andα-SMA in tubulointerstitial by immunohistochemical ways.Finally,we evaluated the correlation among tTG,TGF-β1,andα-SMA protein expression in localization and time phase.All the data of experiment were analyzed by statistics software SPSS 13.0.Results(1) Morphological changes:At day 3,dilated tubule,infiltrated into renal tissues of slight inflammatory cells,and swelling of tubular epithelial cells were observed in untreated group after UUO.It was showed obviously at day 14-21,such as,more tubule were dilated;generous inflammatory cells infiltrated into renal tissue,especially in tubulointerstitial regions;cellulose exudation and tubulointerstitial area broaden.With the experimental session continuing, pathological changes in tubulointerstitial were becoming more and more serious in untreated group after UUO.Compared with control group,there were significant differences in different time points(days 3,7,14 and 28).The extent of tubulointerstitial pathological changes in treated group after UUO is more alleviative than the UUO group(P<0.01),but still more serious than the control group(P<0.01).(2) Expression of tTG,TGF-β1,andα-SMA proteins:①Immunohistochemical staining indicated that tTG and TGF-β1 proteins were expressed slightly in tubule epithelial cellular of control group,and almost no exist in tubulointerstitial regions and glomerular.The mean density of tTG at 3,7,14,28 day were 0.00271±0.00117, 0.00278±0.00124,0.00237±0.00100,0.00220±0.00116,the mean density of TGF-β1 at the four times were 0.00921±0.00161,0.00867±0.00232,0.00919±0.00237,0.00850±0.00213.α-SMA proteins was mainly expressed in vascular wall in tubulointerstitial,and almost no exist in tubulointerstitial regions and glomerular.The mean density was 0.00462±0.00122, 0.00489±0.00145,0.00462±0.00160,0.00455±0.00184 at the four times.There was no difference in all the time points(P>0.05).②Compared with control group,in the model group the expression level of tTG proteins were increased gradually,in tubule epithelial cellular,also in tubulointerstitial regions,α-SMA exist in tubulointerstitial regions,the expression of TGF-β1 proteins peaked at day 14 exist in tubulointerstitial regions and fibroblast,and slight decrease was observed at day 28,the mean density of tTG were 0.00637±0.00152,0.0126±0.0019,0.01 99±0.00203,0.0230±0.00224,the mean density ofα-SMA were 0.0107±0.00243,0.0202±0.002 53,0.0292±0.00360,0.0374±0.00348,the mean density of TGF-β1 were 0.0309±0.00355, 0.0418±0.00533,0.0494±0.00626,0.0475±0.00452,obviously higher than the control group.③The tendency of those factors expression was inhibited in each treated group.Each mean density of the three protein at each observed times were0.00321±0.00108,0.00951±0.00111, 0.0144±0.00159,0.0188±0.00211,0.0364±0.00435,0.0457±0.00435,0.0427±0.00621; 0.00659±0.00145,0.0130±0.00198,0.0162±0.00190,0.0273±0.00193,but still higher than control group(P<0.05).The significant difference were observed between treated and untreated groups in different time points(P<0.01).(3) Correlation analysis:Positive correlations were observed among the observed factors(P<0.01)ConclusionIn the course of tubulointerstitial lesions with young rats,the up-regulated expression of tTG,TGF-β1 andα-SMA exhibit a great malgenic sense,while the benazepril and losartan treatment have a visible interfering effects.