[Evaluation of immune status of kidney transplant recipients by combined HLA-G5 and sCD30].

OBJECTIVE: to study the relationship between the expression of serum human leucocyte antigen-G5 (HLA-G5)/soluble CD30 (sCD30) and the function of renal graft in kidney transplant recipients and investigate the immune status of recipients with combined HLA-G5 and sCD30. METHODS: from January 2002 to November 2008, a total of 66 kidney transplant recipients in our centre were selected as subjects and divided into three groups: stable function of renal graft (n = 38), acute rejection (n = 15) and chronic rejection (n = 13). The expressions of serum HLA-G5 and sCD30 were detected. There were two different immune conditions with acute/chronic allograft rejection and normal renal graft in kidney transplant recipients as evaluated by combined HLA-G5 and sCD30. The sensitivity, specificity and critical value of the method were analyzed by the curve of receiver operating characteristic. RESULTS: the levels of HLA-G5 and sCD30 were significantly correlated with serum creatinine (r = -0.493, 0.691, both P < 0.01). Within the first year post-transplantation, the sensitivity was 78.6% and the specificity 85.7% when HLA-G5 critical value 82 microg/L and sCD30 critical value 12.2 microg/L. After one year post-transplantation: the sensitivity was 92.3% and the specificity 84.6% when HLA-G5 critical value 141 microg/L and sCD30 critical value 10.3 microg/L. CONCLUSION: the immune state of recipients are evaluated by combine HLA-G5 and sCD30 which may be a simple and valid method.

ABCG2 protects kidney side population cells from hypoxia/reoxygenation injury through activation of the MEK/ERK pathway.

Breast cancer resistance protein 1 (BCRP1/ABCG2) is used to identify the side population (SP) within a population of cells, which is enriched for stem and progenitor cells in different tissues. Here, we investigated the role of extracellular signal-regulated kinase (ERK) 1/2 in the signaling mechanisms underlying ischemic/hypoxic conditions in kidney SP cells. Kidney SP cells were isolated using Hoechst 33342 dye-mediated fluorescein-activated cell sorting and then incubated under hypoxia/reoxygenation (H/R) with or without verapamil, a selective BCRP1/ABCG2 inhibitor. ABCG2 expression, ERK activity, cell viability, metabolic activity, and membrane damage were tested after H/R treatment. To evaluate the role of ERK 1/2 on the expression and function of ABCG2, the expression of mitogen-activated protein kinase (MAPK)/ERK kinase (MEK), which preferentially activates ERK, was upregulated by transfection with the recombinant sense expression vector pcDNA3.1-MEK and downregulated by pretreatment with U0126, a specific MEK inhibitor. We found that hypoxia activated ERK activity in the kidney SP cells but not in non-SP cells both in vitro and in vivo. Overexpression of MEK mimicked hypoxia-induced ABCG2 expression. Contrarily, U0126 inhibited hypoxia- and MEK-upregulated ABCG2 expression. Furthermore, H/R induced significant increases in nuclear, metabolic, and membrane damage in both SP cells and non-SP cells; however, this H/R-induced cytotoxicity was much more severe in non-SP cells than in SP cells. Notably, the viability of kidney SP cells was enhanced by MEK overexpression and inhibited by U0126. Verapamil treatment reversed MEK-induced viability of kidney SP cells. When administered systemically into animals with renal ischemia/reperfusion injury, the SP cells significantly improved renal function, accelerated mitogenic response, and reduced cell apoptosis. However, this improved therapeutic potential of SP cells was significantly reduced by pretreatment with verapamil. Collectively, these findings provide evidence for a crucial role for the MEK/ERK-ABCG2 pathway in protecting kidney SP cells from ischemic/hypoxic injury.

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.

[The influence of rapamycin on BTLA expression of human peripheral blood T lymphocytes].

AIM: To explore the effect of rapamycin (RPM) on the expression of B and T lymphocyte attenuate (BTLA) on human peripheral blood T lymphocytes, providing a experimental basis for application of RPM to organ transplantation and autoimmune diseases. METHODS: Human peripheral blood mononuclear cells were isolated by Ficoll density gradient centrifugation, and then the T cells were isolated from PBMCs with immunomagnetic beads. Concanavalin A (Con A) used to stimulate and activate the human peripheral blood T cells. The proliferation of T cells was detected by MTT colorimetry. The levels of IL-2 and IFN-γ in cell culture supernatant were detected by ELISA. The expression of BTLA on T cells was assayed by Flow cytometry. RESULTS: The expression of BTLA on T cells treated with various concentrations (10-1 000 ng/L) of RPM had no significant difference, while had significant difference (P<0.01) by compared with RPM non-treatment group. ELISA detection manifested that compared with the untreated group different concentrations of RPM could significantly inhibit the IL-2 and IFN-γ secretion and significantly inhibited T lymphocyte proliferation (P<0.01). CONCLUSION: RPM has little effect on expression BTLA, but has stronger inhibition on lymphocyte proliferation and inflammatory cytokines secretion. Suggesting that RPM is suitable for the treated of organ transplant rejection and autoimmune diseases.

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

OBJECTIVE: In 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. METHODS: We 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. RESULTS: The 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. CONCLUSION: The 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.