Puxun Tian

Hypoxic preconditioning advances CXCR4 and CXCR7 expression by activating HIF-1α in MSCs.

Recent evidence indicated that sublethal hypoxic preconditioning (HP) of bone marrow-derived mesenchymal stem cells (MSCs) before transplantation could ameliorate their capacity to survive and engraft in the target tissue through yet undefined mechanisms. In this study, we demonstrated that HP (3% oxygen) induced the high expression of both chemokine stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7, in MSCs. HP also improved in vitro migration, adhesion and survival of MSCs. Although SDF-1-induced migration of HP-MSCs was only abolished by an anti-CXCR4 antibody, both CXCR4 and CXCR7 were responsible for elevated adhesion of HP-MSCs. Moreover, CXCR7 but not CXCR4 was essential for the resistance to oxidative stress of HP-MSC. In addition, HP also evoked an increase in expression of hypoxia-inducible factor-1 (HIF-1α) and phosphorylation of Akt. The chemical inducers of HIF-1α, desferrioxamine (DFX) and cobalt chloride (CoCl₂), induced upregulation of CXCR4 and CXCR7 expression in MSCs under normoxic conditions. Contrarily, blockade of HIF-1α by siRNA and inhibition of Akt by either wortmannin or LY294002 abrogated upregulation of HP-induced CXCR4 and CXCR7 in MSCs. Collectively, these findings provide evidence for a crucial role of PI3K/Akt-HIF-1α-CXCR4/CXCR7 pathway on enhanced migration, adhesion and survival of HP-MSCs in vitro.

Mycobacterium tuberculosis Infection in Solid Organ Transplant Recipients : Experience From a Single Center in China

OBJECTIVE We sought to explore the prevalence, clinical manifestations, diagnostic procedures, and treatment of tuberculosis (TB) after solid organ transplantation. PATIENTS AND METHODS In this study, we retrospectively analyzed data of 1947 renal transplant recipients and 85 liver transplant recipients. RESULTS TB developed in 28 organ transplant recipients with a prevalence of 1.38% (28/2032). The median interval between transplantation and development of TB was 32 months (range, 1-142 months). Mycobacterium tuberculosis isolation, histologic signs of caseating granulomas, and TB-DNA detection directly supported the diagnosis in 10 (35.71%), 7 (25.00%), and 5 (17.86%) patients, respectively. In addition, 6 patients (21.43%) highly suspected of TB infection received tentative antituberculosis treatment with favorable responses. Most renal transplant recipients (22/25; 78.57%) received isoniazid, rifampicin (or rifabutin), and ethambutal (or pyrazinamide) for a mean duration of 10 months (range, 6-14 months). Three liver transplant recipients received a different protocol: isoniazid, rifabutin, ethambutal, and ofloxacin for 3 months; then isoniazid and rifabutin for 6 months. Upon follow-up, 8 subjects (28.57%) died; 5 of the deaths were related to TB. During the antituberculosis therapy, toxic hepatitis was seen in 12 patients (42.86%); cyclosporine levels decreased in 15 patients (53.57%); and allograft rejection developed in 6 of them. CONCLUSIONS The peak incidences of TB in liver and kidney transplantations are in the first year and after the first year posttransplantation, respectively. Response to antituberculosis treatment should be considered to make a diagnosis among patients highly suspected of TB infections. Except in special circumstances, antituberculosis treatment protocols including isoniazid and rifampicin for about 10 months seem significantly effective and tolerable for non-liver transplant patients. Fluoroquinolones should be emphasized in posttransplantation TB treatment.

Clinical Application of Cordyceps sinensis on Immunosuppressive Therapy in Renal Transplantation

OBJECTIVE We sought to explore the adjunctive effects of Cordyceps sinensis (CS) in clinical renal transplantation. MATERIALS AND METHODS Patients (n = 202) were divided randomly by lottery into a treatment (n = 93) and a control group (n = 109). Patients in the treatment group were treated with CS 1.0 g 3 times a day in addition to the immunosuppressive regimen given to the control group. We compared patient and graft survivals, incidence, time and severity of acute rejection episodes, chronic allograft nephropathy (CAN), hepatotoxicity and nephrotoxicity, biochemistry parameters including indicators of liver and kidney functions, fats, proteinuria, dosages, and whole blood concentrations of cyclosporine (CsA). RESULTS Patient and graft survival rates, serum creatinine (SCr), and blood urea nitrogen (BUN) were not significantly different between the 2 groups (P > .05). Serum uric acid (UA) and 24-hour urinary total protein (24-hour UTP) were significantly lower in the treatment group than in the control group (P < .05). The incidences (11.83% vs 15.60%) and times to acute renal allograft rejection (23.48 +/- 7.22 vs 22.27 +/- 8.03 days posttransplantation) were not significantly different between the treated and control groups (P > .05). Patients receiving thymoglobulin antirejection therapy (3 cases) were fewer in the heated versus control group (13 cases; P = .014). The incidences of hepatotoxicity and nephrotoxicity in the treated group were 12.90% and 19.35%, significantly lower than 24.77% and 33.94% in the control group, respectively (P < .05). At 2 to 6 months posttransplantation, the CsA dosages in the treated group were significantly lower than those in the control group (P < .05). The whole blood trough CsA concentrations in the treated group were significantly lower than those in the control group at 3 to 6 months posttransplantation (P < .05). The decreasing trends of the 2 aforementioned parameters in the treatment group were approximately linear among treated subjects compared with approximately quadratic in the control group (P < .05). The incidence of CAN in the treated group was 7.53%, which was significantly lower than 18.35% in the control group (P = .024). The 24-hour UTP level in CAN patients within the treated group was significantly lower than the control group after transplantation (P = .045). The differences in total bilirubin, SCr, serum UA, and total cholesterol levels among otherwise normal patients in the treated group were significantly lower than those among the control group (P < .05). CONCLUSIONS The use of CS may allow decreased dosages and concentrations of CsA causing fewer side effects without an increased risk of acute rejection. In addition, CS with reduced dose CsA may decrease proteinuria and retard CAN progression.

Kidney injury molecule-1 and osteopontin: new markers for prediction of early kidney transplant rejection.

BACKGROUND Kidney injury molecule-1 (KIM-1) and osteopontin (OPN) play important roles in immune regulation. We hypothesized that serum KIM-1 and OPN might serve as biomarkers for predicting early acute rejection after kidney transplantation (KTx). METHODS We conducted a single-center study of 155 subjects, who were classified into acute rejection group (ARG, n=32), non-rejection group (NRG, n=45) and healthy controls (HC, n=78). Serum KIM-1 and OPN levels were measured by Luminex. RESULTS The pre-transplant levels of serum KIM-1 and OPN in all KTx recipients were higher than those of HC (P<0.01). Compared with NRG, ARG showed significantly high serum levels of KIM-1 on day 0 (pre-KTx) and on the 1st, 4th, and 7th post-KTx days, and significantly high OPN levels on day 0 and the 7th day. Kaplan-Meier survival analysis showed that the higher levels of KIM-1 on day 0, the 1st and 4th days and OPN on day 0 and the 7th day were significantly associated with the lower probabilities of rejection-free survival. ROC analyses highlight the superiority of KIM-1 on the 1st day and OPN on the 7th day over those on other post-KTx days in prediction of acute rejection episodes. Multivariate logistic analysis revealed that the serum KIM-1 levels on the 1st post-KTx day and the OPN level on the 7th day were independent and powerful predictors of acute rejection episodes. An optimal predictive model was built by combining KIM-1 on the 1st day and OPN on the 7th day, and this model had the highest AUC (0.922). CONCLUSIONS This study was the first to demonstrate that serum KIM-1 and OPN may be the promising and elegant markers for prediction of early acute kidney allograft rejection.

Study on systemic immune tolerance induction in rat islet transplantation by intravenous infusion of Sertoli cells.

Background. Sertoli cells are usually co-transplanted with pancreatic islets to induce local immune tolerance. In this report, we used infusion with Sertoli cells in islet transplantation to induce systemic immune tolerance and studied the mechanism of the tolerance induction. Methods. Streptozotocin-induced diabetic rats were divided into four groups before islet transplantation: group A as control; group B with intravenous infusion of Sertoli cells; group C with Sertoli cell infusion and Fas ligand antibody treatment; and group D with Sertoli cell infusion and transforming growth factor-&bgr;1 antibody treatment. The mean survival time (MST) and insulin expression of islet grafts were measured. The number of lymphocytes and the levels of cytokines in peripheral blood were also measured. Results. Group B had the longest MST of islet allografts (41.6±4.20 days) followed by groups C, D, and A (P<0.05). Immunohistochemistry showed similar results with MST. The rats in group B had the least CD4+ T cells (only 15.6%±6.4%) compared with other groups (P<0.05). The numbers of CD8+ T cells in rats of groups B (11.2%±4.3%) and D (14.5%±5.6%) were significantly lower than those of groups A and C (P<0.05). After transplantation, group Bs interleukin (IL)-2 level (1.92±0.68 ng/mL) was found to be significantly lower than that of other groups (P<0.05). Interferon-&ggr; showed similar pattern of change as IL-2 (P<0.05). Groups A and D had significantly lower levels of IL-4 (4.31±1.97 pg/mL 4.69±1.33 pg/mL, respectively) than groups B and C (P<0.05). Conclusion. Infusion of Sertoli cells could effectively prolong the survival of islet grafts and reduce peripheral blood lymphocyte and cytokine levels. In this process, transforming growth factor-&bgr;1 played a major role and Fas ligand played a smaller additional role.

Magnetic cell sorting and flow cytometry sorting methods for the isolation and function analysis of mouse CD4 + CD25 + Treg cells

ObjectiveIn this paper we compared the two methods of cell sorting (magnetic cell sorting and flow cytometry sorting) for the isolation and function analysis of mouse CD4+ CD25+ regulatory T (Treg) cells, in order to inform further studies in Treg cell function.MethodsWe separately used magnetic cell sorting and flow cytometry sorting to identify CD4+ CD25+ Treg cells. After magnetic cell separation, we further used flow cytometry to analyze the purity of CD4+ CD25+ Treg cells, trypan blue staining to detect cell viability, and propidium iodide (PI) staining to assess the cell viability. We detected the immune inhibition of CD4+ CD25+ Treg cells in the in vitro proliferation experiments.ResultsThe results showed that compared to flow cytometry sorting, magnetic cell sorting took more time and effort, but fewer live cells were obtained than with flow cytometry sorting. The CD4+ CD25+ Treg cells, however, obtained with both methods have similar immunosuppressive capacities.ConclusionThe result suggests that both methods can be used in isolating CD4+ CD25+ Treg cells, and one can select the best method according to specific needs and availability of the methodologies.

TIPE2, a Novel Biomarker for Clinical Chronic Kidney Allograft Rejection

Tumor necrosis factor-a--induced protein 8-like 2 (TIPE2) has an essential role in immune homeostasis, yet the relationship between TIPE2 expression and allograft rejection has not been addressed. Dependent on clinical diagnosis, 96 kidney transplant recipients were divided into three groups, long-term survival group, acute rejection group (AR) and chronic rejection group (CR). Thirty-two healthy volunteers were used as a control group. The expression of TIPE2 in peripheral blood mononuclear cells (PBMC) and kidney biopsy samples was performed using reverse transcript-polymerase chain reaction, immunohistochemistry and immunofluorescence. The expression of TIPE2 in PBMC of CR group was significantly higher than that of the healthy control (P < 0.001), but TIPE2 expression in AR group was lower than that of control individuals (P < 0.05). The renal expression of TIPE2 in allograft tissue of CR was significantly lower and its expression in AR slightly lower than in normal kidneys. The positive correlation between TIPE2 expression in PBMCs and the CR of allo-kidney grafts indicates that detection of TIPE2 in the blood samples may be used as one of the diagnosis molecular markers in clinical monitoring kidney chronic rejection.

Prolongation of Islet Graft Survival Using Concomitant Transplantation of Islets and Vascular Endothelial Cells in Diabetic Rats

BACKGROUND The transplantation of isolated islets of Langerhans is nearing acceptance as treatment of type 1 diabetes mellitus. Because the arterial and venous connections of the pancreas are disrupted during islet isolation, islets must be revascularized after transplantation. OBJECTIVE To observe whether increased numbers of vascular endothelial cells in islets can affect the angiogenesis and function of the grafts. MATERIALS AND METHODS Rats with streptozocin-induced diabetes were divided into 3 groups. The rats in group 1 received islet grafts under the capsule of the left kidney; rats in group 2 received combined vascular endothelial cell and islet transplants; and rats in group 3 served as controls. After the transplantation procedure, blood glucose and insulin concentrations were evaluated daily. Hematoxylin-eosin and immunohistochemical staining was used to detect expression of vascular endothelial growth factor antibodies in the diabetic rat kidneys. The mean microvascular density was also calculated. RESULTS At 3 days posttransplantation, blood glucose and insulin concentrations returned to normal in group 2, however, they declined only slightly in group 1, and moderate hyperglycemia was present. There was a significant difference in blood glucose and insulin concentrations between the 2 groups after 3 days (P < .05). The mean (SD) microvascular density in group 2 was markedly higher than that in group 1 (12.58 [1.81] vs 10.38 [0.97] P = .04). CONCLUSION This study suggests that concomitant transplantation of isolated islets with endothelial cells can prolong islet graft survival in diabetic rats.

Impact of HLA-G 14-bp polymorphism on acute rejection and cytomegalovirus infection in kidney transplant recipients from northwestern China

Human leukocyte antigen (HLA)-G plays an important role in promoting transplant tolerance and helping human cytomegalovirus (CMV) to subvert host defenses. Strong evidence suggests that HLA-G 14-bp insertion/deletion polymorphism influences the stability of HLA-G mRNAs and levels of protein expression. We hypothesized that HLA-G 14-bp polymorphism of recipients has an influence on the risk of acute rejection (AR) and CMV infection. We investigated the impact of HLA-G 14-bp polymorphism on a total of 363 unrelated Chinese Han individuals who included 42 kidney transplant recipients with AR, 43 recipients with CMV infection, 102 recipients with stable allograft function (STA), and 176 healthy controls (HC). No statistically significant difference was found between all kidney transplant patients and HC (P=0.149). But, our data showed an increased frequency of homozygous genotype +14/+14 bp (P(c)=0.004) and allele +14 bp (P(c)=0.002) in patients with AR when compared with STA, with the odds ratio of 3.17 and 2.28, respectively. Moreover, we found that the frequency of the -14/-14 bp genotype (P(c)=0.008) and the -14 bp allele (P(c)=0.016) was increased in patients with CMV infection when compared with STA, with the OR of 2.66 and 1.96, respectively. Multivariate analysis further demonstrated that HLA-G homozygous +14 bp and -14 bp genotypes were an independent risk factor for allograft rejection and CMV infection, respectively. In conclusion, this study identified an important genetic risk factor for acute allograft rejection, and it was the first to show a significant correlation between HLA-G 14-bp polymorphism and CMV infection after kidney transplantation from northwestern China.

Allograft rejection-related gene expression in the endothelial cells of renal transplantation recipients after cytomegalovirus infection.

ObjectiveTo explore the effects of cytomegalovirus (CMV) infection on rejection-related gene expression in the endothelial cells of renal transplantation recipients.MethodsEndothelial cells (ECs) were cultured and stimulated by a variety of factors: A, normal control group; B, inactivated human cytomegalovirus (HCMV) infection group; C, HCMV infection group; D, HCMV supernatant infection group; and E, ganciclovir HCMV group. Expression of intercellular adhesion molecule-1 (ICAM-1) and major histocompability complex (MHC) class I and class II antigens was detected by flow cytometry (FCM) and immunohistochemistry.ResultsWe found characteristic CMV-infected ECs in this study. There were no significant differences among groups A, B and D (P>0.05). Although the expression levels of ICAM-1 were not significantly different between groups C and E (P>0.05), the ICAM-1 expression in these two groups was significantly higher than that in group A (P<0.05). ICAM-1 expression was detected in groups C and E, while there was no expression in groups A, B and D. Furthermore, there was no significant difference of ICAM-1 mRNA expression between groups C and E (P>0.05). Human leucocyte antigen (HLA)-ABC expression was detected in all the groups, while HLA-DR expression was only detected in groups C and E. There were no significant differences of HLA-ABC and HLA-DR expression among groups A, B and D (P>0.05). However, the HLA-ABC and HLA-DR expression levels in groups C and D were higher than those of the remaining groups previously reported (P<0.05). Meanwhile, the HLA-ABC and HLA-DR expression levels in group E were lower than those of group C (P<0.05).ConclusionCMV could up-regulate the expression levels of ICAM-1 and MHC antigens, which was closely related to allograft rejection.