Yangjuan Bai

Meta-analysis of the effect of MDR1 C3435 polymorphism on tacrolimus pharmacokinetics in renal transplant recipients.

BACKGROUND The published data revealed conflicting results of the polymorphism of MDR1 exon 26 SNP C3435T on the pharmacokinetics of tacrolimus in different post transplant times; thus, the aim was to perform a meta-analysis of different post transplant times to investigate the influence of SNP C3435T on the tacrolimus pharmacokinetics. METHODS A literature search was conducted to locate the relevant papers by using the PUBMED and EMBASE electronic source until 2011. The pharmacokinetic parameters, including dose administration, concentration and concentration to dose ratio were extracted and a meta-analysis was performed by using STATA10.0. RESULTS A total of 13 papers concerning 1327 individuals were included in the meta-analysis. The overall results showed SNP C3435T could influence the pharmacokinetic parameters in different post transplant times, the subjects with CC genotype had lower concentration dose ratio and need higher tacrolimus dose than the CT and TT genotype. CONCLUSIONS Our meta-analysis of available studies has demonstrated a definite correlation between the SNP C3435T in MDR1 gene and pharmacokinetics of tacrolimus. However, additional studies with large sample size and better study designs are warranted to verify our finding.

An improved approach for extraction and high-performance liquid chromatography analysis of paraquat in human plasma.

A simple, sensitive, reliable and economical HPLC method for quantifying paraquat concentration in human plasma has been developed, using diethyl paraquat as an internal standard. The drugs were extracted from the sample and separated on Xtimate C18 column with a mobile phase of 15% acetonitrile in 0.1M orthophosphoric acid containing SDS (150 mg/l). The pH of the mobile phase was adjusted to 3 with triethylamine and the detection wavelength was 256 nm for both paraquat and the internal standard. The average extraction recoveries were 91.9%. Good linearity (R(2)=0.9984) was observed throughout the range of 0.02-10 μg/ml in 0.5 ml plasma. The overall accuracy of this method was 97.6-107.3% and the lower limit of detection was 0.01 μg/ml. The intra- and inter-day variations were lower than 3.65% and 2.64%, respectively. We used this method to examine the paraquat concentrations of 53 patients with acute paraquat intoxication of whom 26 (49.1%) survived. In conclusion, this method was suitable for quantification of paraquat plasma concentration in toxicological samples. It was helpful in both assessing the severity of intoxication and predicting the outcome of paraquat poisoning.

The Value of Plasma Paraquat Concentration in Predicting Therapeutic Effects of Haemoperfusion in Patients with Acute Paraquat Poisoning

Objective This study was aimed to analyze the scavenging effect of haemoperfusion on plasma paraquat (PQ) and to evaluate the clinical significance of PQ examination in the treatment of patients with acute paraquat poisoning. Methods 85 patients with acute paraquat intoxication by oral ingestion were admitted in West China Hospital from Jun, 2010 to Mar, 2011. A standardized therapeutic regimen including emergency haemoperfusion was given on all subjects. A total of 91 whole blood samples were taken before (0h), underway (1h after haemoperfusion beginning) and at the end (2h) of the haemoperfusion therapy. The clearance rate was calculated and related factors were analyzed. Results As heamoperfusion was going on, the plasma paraquat concentration of the patients kept falling down. After 1 hour of haemoperfusion, the average clearance rate (R1) was 37.06±21.81%. After 2 hours of haemoperfusion, the average clearance rate (R2) was 45.99±23.13%. The average of R1/R2 ratio was 76.61±22.80%. In the high paraquat concentration group (plasma paraquat concentration (C0) >300 ng/mL), both the averages of R1 and R2 were significantly higher than those of the low paraquat concentration group (C0≤200 ng/mL) (p<0.05), and there was no significant difference of R1/R2 between these two groups (p>0.05). Conclusions The dynamic monitoring of plasma PQ concentration was not only critical in the clinical evaluation but also helpful in guiding the treatment of patients with acute PQ intoxication. Haemoperfusion can effectively eliminate paraquat from the plasma in patients with high initial plasma PQ concentration, while in patients with low initial plasma PQ concentration (<200 ng/ml), the clearance effect of harmoperfusion was very limited. Increasing HP time might improve the overall clearance rate of HP on plasma PQ yet decrease the elimination efficiency of HP, while repeated HP treatment was helpful against the rebound phenomena.

A Significant Expansion of CD8+ CD28- T-Suppressor Cells in Adult-to-Adult Living Donor Liver Transplant Recipients

BACKGROUND The appearance of human regulatory CD8(+) CD28(-) T-suppressor (Ts) cells has been associated with a reduced need for maintenance immunosuppression in cadaveric heart- kidney transplant recipients and pediatric liver-intestine transplant recipients. However, few data are available in adult-to-adult living donor liver transplantation (A-A LDLT). MATERIALS AND METHODS To study the population of CD8(+) CD28(-) Ts cells in A-A LDLT, we performed flow cytometry on whole blood specimens obtained from 20 transplant recipients, 18 end-stage liver disease patients, and 20 normal controls. Meanwhile, we measured the trough levels of immunosuppressants and monitored graft function in transplant recipients. We retrospectively reviewed the clinical data of the 20 recipients. RESULTS A significant expansion of CD8(+) CD28(-) Ts cells was observed among recipients of A-A LDLT as compared with a disease control group (P = .000) or healthy individuals (P = .000). All recipients were free of acute cellular rejection episodes. During the follow-up period, no grafts were lost due to acute or chronic rejection. CONCLUSION Expansion of CD8(+) CD28(-) Ts cells in A-A LDLT seemed to be associated with a decreased occurrence of acute or chronic rejection and sustained good graft function. Based on our low dosages of immunosuppressants for recipients of A-A LDLT, we suggest that this strategy may promote expansion of CD8(+) CD28(-) Ts cells, which can conversely maintain the low immunosuppressant dosages.

CNI induced Th17/Treg imbalance and susceptibility to renal dysfunction in renal transplantation.

Calcineurin inhibitors (CNI) prevent graft rejection by blocking interleukin-2 (IL-2), which was required for development and function of Foxp3(+)CD4(+)CD25(+) regulatory T cells (Treg). Recently, IL-2 was reported to play a part in the inhibition of Th17 cells. The renal transplantation recipient who used CNI regularly might have Th17/Treg imbalance with increased Th17 cells and decreased Treg cells, which would cause renal dysfunction even rejection. To assess the effect of CNI on Th17 cells and Treg cells, we included 123 renal transplantation recipients (101 in a stable stage and 22 with renal dysfunction) and 27 healthy volunteers. Among all the recipients, 103 recipients used CNI and 20 recipients used sirolimus without CNI. The recipients who used CNI were further classified into four groups according to the blood levels of CNI: Of all these subjects, Th17 and Treg frequencies in the peripheral blood were analyzed by flow cytometry (FCM). Serums IL-17, IL-23, IL-6, IFN-r, and TGF-β were analyzed by ELISA. The results demonstrated that the transplantation recipient treated by CNI revealed an obvious increase in peripheral Th17 frequencies and a significant decrease in Treg frequencies when compared with the sirolimus group and healthy people (P<0.05). Even more, the transplantation recipient with renal dysfunction had the highest level of Th17 cells (P<0.05) while the lowest Treg cells compared with stable recipient and healthy control, with increased serums IL-6 and IL-17. Our results indicated that CNI was associated with Th17/Treg imbalance in peripheral blood, which supported the followed generation of renal dysfunction after transplantation.

Impact of tacrolimus on bone metabolism after kidney transplantation.

Bone disease is a common clinical problem after kidney transplantation. To date, studies investigating the effects of tacrolimus (TAC) on bone metabolism in vivo or vitro yielded conflicting data. This study was carried out to discuss the relationship between TAC blood concentrations and bone metabolism status in kidney transplant recipients. 72 kidney recipients whose time since transplantation more than 5 months (5-51 months) were divided into two groups by the TAC blood concentrations, high TAC group (TAC≥6 ng/mL) and low TAC group(TAC<6 ng/mL), respectively. Bone mineral density (BMD) of lumbar vertebrae L1-L4 and neck of the femur and allied biochemical markers (TRAP-5b, B-ALP, 25-(OH)D, PTH, beta-CrossLaps, N-MID Osteocalcin, Ca, PO4) were measured simultaneously. Our results showed that 27.78% of our patients had bone loss and the loss rates were statistical different between the high TAC group and low TAC group in kidney recipients (45.5% vs 20.0%, P=0.026). Correlation analysis showed that TAC concentrations were positively correlated with tartrate-resistant acid phosphatase-5b (TRAP-5b) in male recipients (r=0.287, P<0.05). In conclusion, kidney transplant recipients with high TAC blood concentrations are at risk of bone loss, and TAC may cause bone disorders involved in accelerated bone resorption.

The co-inhibitory pathway and cellular immune imbalance in the progress of HBV infection.

ObjectiveChronic hepatitis B (CHB) affects 400 million people and is the most common cause of liver cirrhosis (LC) and hepatocellular carcinoma (HCC) worldwide. Cellular immune regulation plays an important role in determining the infection outcome. Co-signal molecules and Th17/Treg were studied to explore their association with the progression of HBV infection.MethodsNinety-four HBV-infected patients were categorized into three groups: 31 patients with LC caused by CHB, 30 with HCC caused by CHB and 33 with HCC caused by CHB. Co-signal molecules, Th17/Treg, and Stat3 and Stat5 were analyzed by flow cytometry.ResultsCHB patients who progressed to LC or HCC showed a significantly higher level of co-inhibitory molecules such as BTLA and PD-1, while there was no significant difference in co-stimulatory molecules among LC, HCC and CHB. Stat3 and Stat5 were significantly increased in LC and HCC compared to CHB patients.ConclusionCo-inhibitory molecules play more important roles than co-stimulatory molecules. Increased PD-1 and BTLA/HVEM inhibited immune cells and the immune process. At the same time activated Stat3 and Stat5 stimulate the key factors in differentiation of Th17 and Treg, thus leading to imbalanced expansion of Th17 and Treg; immune tolerance was induced and HBV persistent. This resulted in hepatic inflammation that progressed to cirrhosis and carcinoma.

Regulatory Effect of FK506 on CD152 and PD-1 in the Liver Allorecipients

AIM We dynamically observed the expression of CD152 and PD-1 on T-cell surfaces in peripheral blood of liver allorecipients to explore the regulatory effect of FK506 on negative costimulatory molecules. METHODS We evaluated 20 liver allorecipients, 19 end-stage liver disease patients, and 20 healthy volunteers for FK506 concentrations measured by an enzyme-multiplied immunoassay technique and flow cytometry to determine T-cell subsets as well as CD152 and PD-1 expression. RESULTS After liver transplantation, the frequency of CD4+ T cells gradually decreased to significantly lower level than those in the disease controls (P < .05). CD8+ T cells in each treatment group were obviously higher than those in the disease controls (P < .05). The expression of CD152 on CD4+ and CD8+ T cells was greater than those in healthy controls (P < .05); and at 2 and 4 weeks, higher than those in disease controls (P < .05). The expression of PD-1 on CD4+ T cells from the 2 weeks after treatment was significantly greater than that in healthy controls (P < .05), and that on CD8+ T cells increased obviously from the 4 weeks compared with disease controls (P < .05). CONCLUSION FK506 up-regulated the expression of CD152 and PD-1 on the T-cell surface inhibiting proliferation and activation of effector T cells, favoring the survival of allorecipients.

Correlation of Hla-dp/dq polymorphisms with transplant etiologies and prognosis in liver transplant recipients

Abstract Previous study has identified that the genetic variants in the human leukocyte antigen (HLA)-DP/DQ region were strongly associated with hepatitis B virus (HBV) infection. But their roles in liver function recovery after hepatic transplantation were still obscure. This study aimed to investigate whether HLA-DP/DQ polymorphisms were associated with post-transplant etiologies and prognosis in Chinese liver transplant recipients. A total of 144 liver transplant recipients were enrolled, which were divided into 2 groups according to the transplant etiology: HBV-related disease and non-HBV-related disease. HBV-related disease includes 3 subgroups: liver cirrhosis, hepatocellular carcinoma, and progressive HBV hepatitis. Three single-nucleotide polymorphisms HLA-DP (rs3077 and rs9277535) and HLA-DQ (rs7453920) were studied in all recipients by high-resolution melting curve analysis. Liver function indices (albumin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltranspeptidase, direct bilirubin, total bilirubin) and coagulation indices (prothrombin time, platelet, international normalized ratio, fibrinogen) were routinely tested. After transplant, 10 recipients who were positive for HBsAg or with elevation in HBV virus load were regarded as HBV recurrence. No significant association of HLA-DP/DQ polymorphisms with HBV recurrence or transplant etiology was observed (P < .05). Recipients with HLA-DQ (rs7453920) AG and AA genotype had lower direct bilirubin levels than GG genotype individuals, especially on the 14th day after surgery (17.80 vs. 5.35, P  =  .038). Patients with A alleles displayed earlier liver function recovery than patients with G alleles (7 vs. 6 months). No significant correlation was shown in HLA-DP rs3077 and rs9277535 with HBV infection or liver function recovery (P < .05). Our study concluded that HLA-DP (rs3077 and rs9277535) and HLA-DQ (rs7453920) were not significantly associated with HBV recurrence or HBV susceptibility, but HLA-DQ rs7453920 was related to prognosis of liver transplant recipients. HLA-DQ rs7453920 A might be used as an indicator of earlier recovery and better prognosis after transplantation.

Sirolimus-based regimen promotes inhibitory costimulatory signal of HVEM/BTLA/CD160/LIGHT pathway in allo-renal recipients.

HVEM/BTLA/CD160/LIGHT pathway is a very special costimulatory molecule system which can regulate T-cell immune responses by activating both inflammatory and inhibitory signalings. The regulatory effect of Sirolimus on HVME costimulatory system in allo-renal recipients has not been reported. In this study, we analyzed the expression of HVEM, BTLA, CD160 and LIGHT on circulating T cell subgroups and the expression of HVEM on CD4+ Tregs by flow cytometry and also the pre-dose concentration of Sirolimus by automatic analyzer. Both the allo-renal recipients receiving Sirolimus immunosuppressive regimen and health volunteers were included. The expression of both BTLA and CD160 on T cells increased significantly while the expression of LIGHT on T cells decreased significantly in allo-renal recipients receiving Sirolimus regimen (p<0.05). The expression of HVEM on T cells and CD4+ T-cell subgroup decreased (p<0.05) while that on CD8+ T-cell subgroup remained roughly normal (p>0.05).The expression of HVEM on CD4+ Tregs increased significantly (p<0.05) in allo-renal recipients receiving Sirolimus regimen (p<0.05). Though regulating the expression of HVEM/BTLA/CD160/LIGHT costimulatory system, Sirolimus-based regimen promotes inhibitory costimulatory signal in T cells and enhances the function of CD4+ Tregs in allo-renal recipients, which are in benefit of the control of transplant rejection as well as the induction and maintenance of transplant tolerance.