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Biomedical subjects

Guang Yu

Publications and source records attributed to Guang Yu.

12 recordsLinked to original sources
PubMed2006

NK cells promote transplant tolerance by killing donor antigen-presenting cells.

Natural killer (NK) cells are programmed to kill target cells without prior antigen priming. Because of their potent cytolytic activities, NK cells are one of the key cell types involved in dismantling allografts. However, in certain transplant models, NK cells also express potent immunoregulatory properties that promote tolerance induction. The precise mechanism for such striking dichotomy remains unknown. In the present study, we showed in a skin transplant model that the skin allografts contain a subset of antigen-presenting cells (APCs) that can home to the recipient mice. We also showed that such graft-derived APCs are usually destroyed by the host NK cells. But in the absence of NK cells, donor APCs can survive and then migrate to the host lymphoid and extralymphoid sites where they directly stimulate the activation of alloreactive T cells. T cells activated in the absence of NK cells are more resistant to costimulatory blockade treatment, and under such conditions stable skin allograft survival is difficult to achieve. Our study identified a novel role for NK cells in regulating T cell priming in transplant models, and may have important clinical implications in tolerance induction.

Adoptive Transfer↗
PubMed2006

Ephrin-B1 is critical in T-cell development.

Eph kinases are the largest family of receptor tyrosine kinases, and their ligands, ephrins (EFNs), are also cell surface molecules. In this study, we investigated the role of EFNB1 and the Ephs it interacts with (collectively called EFNB1 receptors) in mouse T-cell development. In the thymus, CD8 single positive (SP) and CD4CD8 double positive (DP) cells expressed high levels of EFNB1 and EFNB1 receptors, whereas CD4 SP cells had moderate expression of both. Soluble EFNB1-Fc in fetal thymus organ culture caused significant subpopulation ratio skew, with increased CD4 SP and CD8 SP and decreased DP percentage, while the cellularity of the thymus remained constant. Moreover, in EFNB1-treated fetal thymus organ culture, CD117(+), CD25(+), DP, CD4 SP, and CD8 SP cells all had significantly enhanced proliferation history, according to bromodeoxyuridine uptake. In vitro culture of isolated thymocytes revealed that EFNB1-Fc on solid-phase protected thymocytes from anti-CD3-induced apoptosis, with concomitant augmentation of several antiapoptotic factors, particularly in CD4 SP and CD8 SP cells; on the other hand, soluble EFNB1-Fc promoted anti-CD3-induced apoptosis, as was the case in vivo. This study reveals that EFNB1 and EFNB1 receptors are critical in thymocyte development.

Animals↗
PubMed2005

Tumor vaccine based on cell surface expression of DcR3/TR6.

DcR3/TR6, a secreted protein belonging to the TNF receptor superfamily, interacts with lymphotoxin-like, exhibits inducible expression, and competes with herpes simplex virus glycoprotein D for herpes virus entrance mediator (LIGHT), Fas ligand (FasL), and TL1A, all members of the TNF superfamily. Solid-phase TR6 can trigger reverse signaling of LIGHT and FasL expressed on T cells, and lead to T cell costimulation. In this study, we engineered tumor cells to express cell surface TR6 and used these cells as a tumor vaccine. We demonstrated that mastocytoma P815 cells expressing surface TR6 (TR6-P815) effectively augmented the T cells response in vitro and ex vivo in terms of proliferation, as well as IL-2 and IFN-gamma secretion. TR6-P815 cells had reduced tumorigenicity compared with parental P815 cells. When inactivated TR6-P815 cells were employed as a vaccine, they protected the mice from challenge with live parental P815 cells, and eliminated established P815 tumors. The cell surface TR6-based tumor vaccine was also effective against low antigenicity tumors, such as B16 melanoma; co-administration of bacillus Calmette-Guérin further enhanced the vaccine's efficacy. Thus, cell surface TR6 expression is a useful addition to our tumor vaccine arsenal.

Animals↗
PubMed2005

[Analysis of authors of articles published in Chinese Journal of Ophthalmology from 1995 to 2004].

OBJECTIVE: We aimed to analyze the authors, the organizations and regional distribution of these authors of Chinese Journal of Ophthalmology, and ascertain the core authors, core organizations and core regions. METHODS: Using quantitative analysis method, we analysed the authors, co-authors and the core authors of papers published between 1995 to 2004. Also, the distributions of districts and highly quantitative organization were determined statistically. RESULTS: There were 2143 articles published during the last ten years; 912 author had published only one paper, accounted for 70.59% of total first authors. There were 1853 articles with one or more co-authors, the cooperative rate and degree were 86.47% and 3.56, respectively. There were 290 papers with single author, which accounted for 13.53% of total papers. The number of papers from universities, institutes, affiliated hospitals and hospitals were 246 (11.48%), 176 (8.21%), 969 (45.22%) and 423 (19.74%), respectively. There were 82 core authors published 553 (25.81%) papers, while 20 highly-quantities organizations published 1016 (47.41%) papers. Core region was Beijing, which published 574 (26.78%) articles. CONCLUSIONS: Authors of the Chinese Journal of Ophthalmology have a wide distribution and highly cooperative rate. There are a group of active and talented core authors, who have a great influence on this journal.

Authorship↗
PubMed2005

Gene delivery of SOCS3 protects mice from lethal endotoxic shock.

Suppressor of cytokine signaling 3 (SOCS3) was reported as a feedback inhibitor of cytokine receptor signaling by inhibiting the JAK-STAT signal transduction pathway. We sought to test the anti-endotoxic septic shock effect of liposome mediated gene delivery of SOCS3 in a lethal endotoxic shock mouse model. BALB/c mice were injected intraperitoneally with 200 microg pcDNA3.1-SOCS3 cationic liposomes, while pcDNA3.1-IL-10 and empty vector as positive and negative control respectively. Forty-eight hours after gene delivery, mice were challenged with 4 microg of E.coli 0127:B8 LPS and 18 mg D-GalN administered i.p. 90 min later, serum TNF-alpha level was determined. Survival over the next 48 h was evaluated. Peritoneal macrophages from survival mice were stimulated in vitro with 1 ug/ml LPS for 18 h, and the supernatants were harvested for determination of the amount of TNF-alpha. We found that gene delivery of SOCS3 significantly increase the mouse survival rate from 27.8 +/- 9.6% of control group to 61.1 +/- 9.6% (p < 0.01). In comparison with control group (218 +/- 13 pg/ml) and sham delivery group (2,122 pg/ml), gene delivery of SOCS3 reduced the level of serum TNF-alpha (68 +/- 9 pg/ml) significantly (p < 0.01). Furthermore, gene delivery of SOCS3 displayed the capacity of prevention of tolerance of peritoneal macrophages to LPS. These findings suggest that gene delivery of SOCS3 mediated by liposome is a promising approach for endotoxic septic shock treatment.

Animals↗
PubMed2004

EphrinB1 is essential in T-cell-T-cell co-operation during T-cell activation.

Eph kinases are the largest family of receptor tyrosine kinases, and their ligands are ephrins (EFNs), which are also cell surface molecules. We have very limited knowledge about the expression and function of these kinases and their ligands in the immune system. In this study we investigated the effect of EFNB1 on mouse T-cells. EFNB1 and the Eph kinases it interacts with (collectively called EFNB1 receptors (EFNB1R)) were expressed on T-cells, B cells, and monocytes/macrophages. Some T-cells were double positive for EFNB1 and EFBB1R. Solid phase EFNB1 in the presence of suboptimal TCR ligation augmented T-cell responses in terms interferon-gamma secretion, proliferation, and cytotoxic T lymphocyte activity but not interleukin-2 production. After T-cell receptor (TCR) ligation, EFNB1R congregated to TCR caps, and then both of them translocated to raft caps. This provides a morphological basis for EFNB1R to enhance TCR signaling. Further downstream of the signaling pathway, EFNB1R stimulation led to increased LAT (linker for activation of T-cells) phosphorylation and p44/42 and p38 MAPK activation. Similar to CD28 costimulation, EFNB1R costimulation was insensitive to cyclosporin A inhibition. On the other hand, unlike the former, EFNB1R costimulation failed to activate Akt, which is essential in triggering interleukin-2 production. Our study suggests that EFNB1 is pivotal in T-cell-T-cell costimulation and in reducing T-cell response threshold to antigen stimulation.

Animals↗
PubMed2004

EphB6-null mutation results in compromised T cell function.

So far, there is very limited knowledge about the role of Eph kinases, the largest family of receptor tyrosine kinases, in the immune system. Here, using EphB6(-/-) mice, we demonstrated that in vitro and in vivo T cell responses such as lymphokine secretion, proliferation, and the development of delayed-type skin hypersensitivity and experimental autoimmune encephalitis in EphB6(-/-) mice were compromised. On the other hand, humoral immune responses, such as serum levels of different Ig isotypes and IgG response to tetanus toxoid, were normal in these mice. Mechanistically, we showed that EphB6 migrated to the aggregated TCRs and rafts after TCR activation. Further downstream, in the absence of EphB6, ZAP-70 activation, LAT phosphorylation, the association of PLCgamma1 with SLP-76, and p44/42 MAPK activation were diminished. Thus, we have shown that EphB6 is pivotal in T cell function.

Animals↗
PubMed2004

[Effect of integrated traditional Chinese and Western medicine therapy on progression of acute renal failure in patients with chronic renal insufficiency: a short-term clinical study].

OBJECTIVE: To evaluate the effect of integrated traditional Chinese and Western medicine therapy on the progression of acute renal failure in patients with chronic renal insufficiency. METHODS: Thirty-two patients with chronic renal insufficiency developed acute renal failure recently were treated with Chinese herbs and western drugs intravenously and clysterizing of Chinese herbs liquid for 30 minutes, and the treatment course was 14 days. Assessment of liver and renal function, blood routine, electrolytes and endogenous creatinine clearance rate (Ccr) was performed before and 2 weeks after the treatment. RESULTS: The levels of hemoglobin (HB), white blood cell count (WBC) and serum electrolytes showed no significant changes after the treatment. The levels of blood urea nitrogen (BUN) and serum creatinine (SCr) decreased, while the level of Ccr increased significantly (P<0.05) after the treatment. The total effective rate was 65.6%. CONCLUSION: The integrated traditional Chinese and Western medicine therapy can effectively delay the deterioration of renal function in patients with chronic renal insufficiency accompanied by acute renal failure.

Acute Kidney Injury↗
PubMed2003

Mouse ephrinB3 augments T-cell signaling and responses to T-cell receptor ligation.

Ephrins (EFN) are cell-surface ligands of Ephs, the largest family of cell-surface receptor tyrosine kinases. The function of EFNs in the immune system has not been well studied, although some EFNs and Ephs are expressed at high levels on certain leukocytes. We report here that EFNB3 and its receptors (collectively called EFNB3Rs, as EFNB3 binds to multiple EphBs) were expressed in peripheral T cells and monocytes/macrophages, with T cells being the dominant EFNB3+ and EFNB3R+ cell type. Solid-phase EFNB3-Fc in the presence of suboptimal anti-CD3 crosslinking enhanced T-cell responses in terms of proliferation, activation marker expression, interferon-gamma but not interleukin-2 production, and cytotoxic T-cell activity. EFNB3R costimulation in the presence of phorbol 12-myristate 13- acetate was insensitive to cyclosporin A, similar to CD28 costimulation, suggesting they might share a part of the signaling pathway. After crosslinking, T-cell receptor and EFNB3R congregated into aggregated rafts, and this provided a morphological basis for signaling pathways of T-cell receptor and EFNB3R to interact. Solid-phase EFNB3-Fc augmented p38 and p44/42 MAPK activation further downstream of the signaling pathway. These data suggest that EFNB3 is important in T-cell/T-cell and T-cell/antigen-presenting cell collaboration to enhance T-cell activation and function.

Animals↗
PubMed2003

Ephrin B2 induces T cell costimulation.

Eph kinases form the largest family of receptor tyrosine kinases, and their ligands are ephrins (EFNs), which are cell surface proteins. Some Eph kinases and EFNs are expressed on T cells, B cells, and dendritic cells, but their functions in the immune system are largely unknown. In this study, we investigated the effect of EFNB2 on murine T cells. EFNB2 mRNA was expressed in the cortex of the thymus and white pulp of the spleen. At the protein level, it was expressed on T cells and monocytes/macrophages, but not on B cells. EFNB2Rs were expressed mainly on T cells. Solid-phase EFNB2 along with suboptimal anti-CD3 strongly stimulated T cell proliferation, with concomitant augmentation of IFN-gamma but not IL-2 or IL-4 secretion. The activity of cytotoxic T cells was also significantly enhanced in the presence of solid-phase EFNB2. These results indicate that EFNB2R cross-linking results in costimulation of T cells. EFNB2Rs were normally scattered on the T cell surface; after TCR cross-linking, they rapidly congregated to capped TCR complexes and then to patched rafts. This provides a morphological base for EFNB2Rs to participate in T cell costimulation. We also demonstrated that EFNB2R signaling led to augmented p38 and p44/42 mitogen-activated protein kinase activation. Our study shows that EFNB2 plays important roles in immune regulation.

Adjuvants, Immunologic↗
PubMed2002

EphB6 crosslinking results in costimulation of T cells.

Erythropoietin-producing hepatocyte (Eph) kinases represent the largest receptor tyrosine kinase family. Some of them are expressed in the T cell compartment, but their function in T cells is unknown. In peripheral blood, EphB6 was predominantly expressed on T cells, and was upregulated after culture. EphB6 crosslinking by anti-EphB6 mAb or ephrinB2 in the presence of suboptimal T cell receptor (TCR) stimulation led to drastic T cell proliferation, suggesting that EphB6 can co-stimulate T cells. The proliferation was accompanied by enhanced production of several lymphokines, such as IFN-gamma, IL-6, IL-10, TGF-beta, TNF-alpha, and GM-CSF, but not IL-2 and IL-4. Sorted EphB6(+) T cells had significantly stronger response to anti-CD3 and anti-CD28 stimulation than EphB6(-) T cells had. Taken together, these data suggest an important role of EphB6 in normal T cell activation. Within two minutes of anti-CD3 and anti-CD28 stimulation, EphB6 aggregated and colocalized with TCR, and this provides a morphological basis for EphB6 to enhance TCR signaling. The capping was followed by p38 MAPK activation, showing that EphB6 is capable of signaling, in spite of its lack of intrinsic kinase activity. This study demonstrates that interaction between EphB6 and its ligands facilitates T cell responses to antigen.

Animals↗