The expression mechanism of programmed cell death 1 ligand 1 and its role in immunomodulatory ability of mesenchymal stem cells / 中华创伤杂志(英文版)

Programmed cell death 1 ligand 1 (PD-L1) is an important immunosuppressive molecule, which inhibits the function of T cells and other immune cells by binding to the receptor programmed cell death-1. The PD-L1 expression disorder plays an important role in the occurrence, development, and treatment of sepsis or other inflammatory diseases, and has become an important target for the treatment of these diseases. Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cells with multiple differentiation potential. In recent years, MSCs have been found to have a strong immunosuppressive ability and are used to treat various inflammatory insults caused by hyperimmune diseases. Moreover, PD-L1 is deeply involved in the immunosuppressive events of MSCs and plays an important role in the treatment of various diseases. In this review, we will summarize the main regulatory mechanism of PD-L1 expression, and discuss various biological functions of PD-L1 in the immune regulation of MSCs.

Serum 25-hydroxyvitamin D concentration is negatively related to carotid artery intima-media thickness in type 2 diabetic patients / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the relationship between 25-hydroxy vitamin D [25(OH)D] and carotid artery intimal medial thickness (IMT) in type 2 diabetic (T2DM) patients.</p><p><b>METHODS</b>Serum 25(OH)D and carotid IMT were measured in 300 T2DM patients. Patients were divided into four quartile groups according to the serum 25(OH)D levels (Q1: < 26.17 nmol/L, 74 cases; Q2: 26.17 - 32.75 nmol/L, 76 cases; Q3: 32.75 - 42.93 nmol/L, 78 cases; Q4 > 42.93 nmol/L, 72 cases).</p><p><b>RESULTS</b>Carotid IMT, carotid artery plaque prevalence, duration of diabetes, HbA1c, CRP and PTH were significantly higher in subjects with low 25(OH)D compared subjects with high 25(OH)D (P < 0.05). Carotid artery IMT in Q1 and Q2 groups were significantly higher than that in Q4 group (1.03 ± 0.21 vs. 0.90 ± 0.20, 1.01 ± 0.26 vs. 0.90 ± 0.20, P < 0.05), was similar among Q1 and Q2 and Q3 groups. Prevalence of carotid atherosclerotic plaque in Q1 group (50.0%) was also significantly higher than in Q3 (29.5%, P < 0.05) and Q4 (16.7%, P < 0.05). Similarly, 25(OH)D concentration was significantly lower in patients with carotid plaque compared patients without carotid plaque [(28.31 ± 4.91) nmol/L vs. (36.31 ± 4.31) nmol/L, P < 0.01]. Pearson correlation analysis showed that carotid IMT was positively correlated with age, smoking, BMI, HbA1c, CRP, LDL-C, PTH/25(OH)D ratio (P < 0.05), and was negatively correlated with 25 (OH) D (r = -0.51, P < 0.01). Multivariate regression analysis showed that 25(OH)D concentration was an independent predictor of carotid IMT in this cohort (β = -0.39, P < 0.01).</p><p><b>CONCLUSION</b>Serum 25(OH)D concentration is negatively correlated with carotid IMT and low 25 (OH) D level is a risk factor for preclinical atherosclerosis in T2DM patients.</p>

Stable cell line for secretion of replication-defective hepatitis B virus vector expressing blasticidin resistant gene / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To construct a stable cell line with permanent secretion of recombinant hepatitis B virus (HBV) vector, which express blasticidin resistant gene.</p><p><b>METHODS</b>Replication-defective HBV vector, pCH-BsdR, which express blasticidin resistance gene was constructed by deleting the HBV genes and inserting the blasticidin resistance gene into the S region. The G418-resistant, the packaging signal deleted HBV helper plasmid, pcDNA3.1-CH3142, and the HBV vector pCH-BsdR were cotransfected into HepG2 cells. Cell clones were selected by the adding of both blasticidin and G418, then serial detection were done.</p><p><b>RESULTS</b>After 36 cell clones were picked and expanded. Three cell clones were defined as the best. Quantity of their HBV DNA were 4.1 x 10(6), 3.6 x 10(6) and 1.2 x 10(6) copies/ml, respectively. Enveloped recombinant, but not wild type HBV were confirmed in the culture medium.</p><p><b>CONCLUSIONS</b>The stable cell lines can realize large preparation of recombinant HBV virions. This will contribute to the use of HBV vector for gene therapy and HBV susceptible cell lines screening.</p>

Development of monoclonal antibodies against SARS-CoV and identification of antigenic epitopes / 生物工程学报

Based on the genomic sequence of SARS-CoV strain BJ101, antigenic immunodominant genes coding for the structure proteins of SARS-CoV were predicted by bio-informatics methods, and two chimeric genes A and B with multi-immunodominants lined up by Gly-Pro-Gly linker were synthesized. The chimeric genes were cloned into plasmid pGEX-6p-1 and expressed in E. coli with IPGT inducing. BALB/c mice were immunized with the purified recombinant fusion protein. The specificity of monoclonal antibodies were tested with a commercial ELISA kit for detecting antibody against SARS-CoV. The results showed that two peptides with molecular weights of 34kD and 35kD expressed by the two chimeric genes could be recognized by SARS patient convalescent serum in Western blot. Six positive hybridoma cell lines stably secreting monoclonal antibodies were selected. The subtype of monoclonal antibody D3C5 is IgG2a, and subtypes of all other five monoclonal antibodies are IgG1. Light chains of all monoclonal antibodies are kappa. With a commercial SARS-CoV antibodies detection ELISA kit, five out of six monoclonal antibodies were positively recognized. In western blot analysis with inactived virus cultures, D3D1 specifically recognized a band of about 180 kD. To further analyse the epitopes corresponding to the monoclonal antibodies, six oligoes (S1-S6) from S gene were synthesized and expressed. The results showed that the monoclonal antibodies D3D1 and D3C5 specifically recognized expression product of S2 and S5 oligoes, respectively. The S2 and S5 oligoes are corresponding to 447-458aa and 789-799aa of SARS-CoV S protein respectively.