Study On The Relationship Between Transforming Growth Factor Beta-1 Gene Polymorphisms And Chronic Allograft Nephropathy

Chronic allograft nephropathy(CAN) is the main cause of renal allograft loss . Cytokine plays an important effect of cell activation, migration, multiplication , effect in chronic allograft nephropathy and leads to organ fibrosis and function loss .Transforming growth factor beta-l(TGF-β1) is the principal fibrogenetic cytokine . TGF-Bl gene polymorphisms determine the amount of cytokine production in body . The TGF-β1 gene polymorphisms ( position +869 and position +915) have the change of T/C, G/C. And there are nine kinds of allele in TGF-Bl gene including T/T G/G, T/C G/G, T/C G/C, C/CG/G, T/T G/C, C/C G/C, C/C C/C, T/T C/C and T/C C/C. According to the relationship between cytokine production and genotype ,the higher intermediate and low production type are determined . High production type in TGF-βl gene is T/T G/G, T/C G/G ( position +869 and position +915). Intermediate production type in TGF-Bl gene is T/C G/C, C/C G/G, T/T G/C (position +869 and position +915).Low production type in TGF-β1 gene is C/C G/C, C/C C/C, T/T C/C, T/C C/C ( position +869 and position +915). Homozygote of high production genotypes produce cytokine the most highly. Homozygote of low production genotypes produce cytokine the most lowly .Heterozygote of high production genotypes and low production genotypes produce intermediate cytokine.The TGF-β1 concentration of high production genotypes in serum is three to ten times of intermediate low production genotypes. Different production can affect occurrence and development of diseases . It had been reported that cytokine gene polymorphisms correlated with the development of transplanted organs .From recent research - there was no relationship found between TGF-β1 gene polymorphisms and the incidence of acute rejection in transplanted renal .The relationship of TGF-β1 gene polymorphism and chronic allograft nephropathy was still not reported internallyObjective The aim of this study is to investigate whether TGF-131 gene polymorphism influence the incident and severity of chronic allograft nephropathy.Methods Fifty cases of failed renal allografts completed in our center defined clinically and confirmed histopathologically were observed as CAN group simultaneously a retrospective case-control study was performed on fifty renal transplant recipients with normal graft function observed as a control group. Both of two groups TGF-β1 genotype ( position +869 ,codon 10 and position +915 ,codon 25) were detected . DNA was extracted from paraffin specimens of patients in CAN group and whole blood of patients in control group . After amplification with polymerase chain reactions with specific designed sequence primer and purification ,the TGF-β1 +869 and +915 were determined using DNA analyzer . The distribution frequencies of high production genotypes was then compared between two groups . TGF-β1 expressions were studied in chronic allograft nephropathy kidney tissues by means of immunohistochemical ABC method. The staining intensity was compared between high production genotype group and intermediate low production genotype group.Further .according to banff classification and lesion scoring in renal allograft pathology ,a pathological study was on removed allograft kidney.Results High production genotype was higher in the CAN group than the control group (70%(35/50) VS 38%(19/50), x2=10.306 P=0.001).In order to find out other risk factors influenceing chronic allograft nephropathy and eliminate disturbance . The follow factors were compared between the CAN group and the control group :gender -. age^ human leukocyte antigen matclu delayed graft function acute rejectionn immunosuppressive regimen > cytomegalovirus infection>. hypertension high cholesterin .Only acute rejection was probably different in two groups (x2=3.175 P=0.075) . In order to avoid disturbance, further classified according to acute rejection ,in CAN group and control group with acute rejection ,the frequencies of high production genotypes were 72.2% and 30% respectively ,there was different between two groups (P=0.049). The frequencies of high production genotypes without acute rejection in CAN group was higher than the control group (68.8%VS 40%, x2=5.896 P=0.015). Mantel-Haenszel test showed that the rate of high production genotype in the CAN group was significantly higher than in the control group (p=0.542) . Estimating staining intensity by half ration method :no staining cell ( — ), staining cells below 25% ( +), staining cells from 25 % to 50 % % (+ +), staining cells greater than 50 %( + + + ), staining cells greater than 75 % ( + + + + ) . The distributions of staining ++grade , + + +grade , + + + +grade in TGF-61 high production genotype group and intermediate low production genotype group were 2 cases > lOcases >. 23cases and 6cases -. 8cases - leases respectively. TGF-81 high production genotype had higher distributions of TGF-61 in kidney allograft(Mann-Whitney test, p=0.542). According to the Banff 97 working classification of renal allograft pathology :Grade I mild interstitial fibrosis and tubular atrophy without or with specific changes suggesting chronic rejection , Grade II moderate interstitial fibrosis and tubular atrophy without or with specific changes suggesting chronic rejection , Grade Illsevereinterstitial fibrosis and tubular atrophy and tubular loss without or with specific changes suggesting chronic rejection . The distribution s of banff classification I grade , II grade , III grade in TGF-Bl high production genotype group and intermediate low production genotype group were 4 cases > lOcases ^ 21cases and 4 cases ^ 7cases > 4cases respectively (Mann-Whitney test, p=0.03).TGF-81 high production genotype group developd more severely in histological changes than the intermediate low production genotype group.Conclusions The TGF-61 high producer genotype associated with CAN ,maybe a risk factor for CAN . Patients with TGF-Bl high producer genotype are more likely to suffer from chronic allograft nephropathy after renal transplantation .A great deal of TGF-Bl cytokine deposit in chronic allograft nephropathy kidney tissues . TGF-Bl high producer genotype express higher than intermediate low production genotype. High production genotype develop severely than intermediate low production genotype. There were correlation between TGF-Bl expression level and fibrogenetic grade in transplanted kidney . TGF-Bl genotype may be a index to predict the occurrence risk of chronic allograft nephropathy after kidney transplantation .For the patients with TGF-Bl high producer genotype, treatment with medicine decreaseing plasma levels of TGF-Bl will improve the long tern survial rate of renal allografts .Routine screening of gene polymorphism may have a clinical role in identify patients at risk of rejections and may be beneficial to choose feasible immunosuppressive regimen or individualizing immunosuppression . Detection of cytokine genotype is easier and more stable than detection of cytokine concentration in body ,and will be a routine test before transplantation .