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Biomedical subjects

Qing Yi

Publications and source records attributed to Qing Yi.

At least 19 recordsLinked to original sources
PubMed2006

Optimizing immunotherapy in multiple myeloma: Restoring the function of patients' monocyte-derived dendritic cells by inhibiting p38 or activating MEK/ERK MAPK and neutralizing interleukin-6 in progenitor cells.

Previous studies demonstrated that circulating dendritic cells (DCs) in myeloma patients were functionally abnormal. However, the phenotype and function of patients' monocyte-derived DCs (MoDCs), which are commonly used for immunotherapy, were poorly defined. This study was undertaken to examine the quality of MoDCs from myeloma patients compared with cells from healthy donors. We found that patient-derived MoDCs are phenotypically and functionally defective. Compared with their normal counterparts, patient-derived, mature MoDCs expressed significantly lower levels of CD1a, CD40, CD80, and HLA-DR and were poor at activating alloreactive T cells, presenting recall antigen, and activating autologous antigen- and myeloma-specific T cells. These abnormalities may be attributed to elevated production of autocrine cytokines such as IL-6, activated p38 and STAT3, and inhibited MEK/ERK signaling pathways in the progenitor cells. Treatment with neutralizing IL-6-specific antibody and, more importantly, p38 inhibitor, or both, could correct these abnormalities. Treating patient-derived cells with these agents not only significantly increased cell yield but also produced MoDCs that were as functional as their normal counterparts. Thus, this study has delineated the mechanistic defects of MoDCs from myeloma patients and identified ways for restoring the function of the cells to improve the efficacy of DC-based immunotherapy in this disease.

Antibodies↗
PubMed2006

Targeting beta2-microglobulin for induction of tumor apoptosis in human hematological malignancies.

We discovered that monoclonal antibodies (mAbs) specific to human beta(2)-microglobulin (beta(2)M) induce apoptosis in vitro and were therapeutic in mouse models of myeloma and other hematological tumor cells. Cell death occurred rapidly, without the need for exogenous immunological effector mechanisms. The mAbs induced cell death via recruiting MHC class I molecules to lipid rafts and activating Lyn and PLCgamma2, leading to activated JNK and inhibited PI3K/Akt and ERK, compromised mitochondrial integrity, and caspase-9-dependent cascade activation. Although the expression of beta(2)M on normal hematopoietic cells is a potential safety concern, the mAbs were selective to tumor-transformed cells and did not induce apoptosis of normal cells. Therefore, such mAbs offer the potential for a therapeutic approach to hematological malignancies.

Animals↗
PubMed2006

Automated classification and quantification of F-actin-containing ruffles in confocal micrographs.

Membrane ruffles are actin-rich protrusions of the plasma membrane that can be observed on the surface of many cell types. Phase contrast and fluorescent microscopy are widely used in the analysis of ruffles, which are commonly identified in cells stained with fluorescently labeled phalloidin. Currently, comparison of cellular ruffle formation under different experimental conditions is generally qualitative or semiquantitative. Ruffle structures are often defined using manual tracing and thresholding methods. Here, we report the rapid and accurate segmentation of ruffles from two-dimensional confocal projections of cells using automated method based on well-established image processing and analysis methods. Line-shaped ruffles were detected using line detectors and were then separated from the filtered images. Automated categorizing of the segmented line structures enabled accurate quantification of the ruffles. This automated approach is efficient and reliable and hence can serve as a powerful tool in studies of the mechanism of ruffle formation.

Actins↗
PubMed2005

Targeting heat shock proteins for immunotherapy in multiple myeloma: generation of myeloma-specific CTLs using dendritic cells pulsed with tumor-derived gp96.

PURPOSE: To develop effective immunotherapies for patients with multiple myeloma, it is important to use novel tumor antigens. Recent studies in solid tumors show that tumor-derived heat shock proteins (Hsp) can be used as immunogen; however, no such study has yet been reported in multiple myeloma. EXPERIMENTAL DESIGN: We examined whether myeloma-derived Hsp gp96 can be used as a myeloma antigen. Specific CTL lines were obtained after repeatedly stimulating T cells with autologous, HLA-A*0201+ dendritic cells pulsed with gp96 derived from HLA-A*0201+ human myeloma cell line (HMCL) U266 or primary myeloma cells. RESULTS: These T cells lysed not only gp96-pulsed dendritic cells, U266, and other HLA-A*0201+ HMCLs IM-9 and XG1 but also effectively killed HLA-A*0201+ primary myeloma cells from patients. No killing was observed against unpulsed dendritic cells, dendritic cells pulsed with control gp96, HLA-A*0201- HMCLs, and primary myeloma cells, or HLA-A*0201+ nonmyeloma cells. Cytotoxicity was mainly MHC class I/HLA-A*0201 restricted, suggesting that the CTLs recognized gp96-chaperoned peptides on HLA-A*0201 that were derived from shared myeloma antigens and that myeloma cells naturally present these peptides in the context of their surface MHC molecules. Upon antigen stimulation, these T cells secreted IFN-gamma and tumor necrosis factor-alpha, indicating that they belong to type 1 T-cell subsets. CONCLUSION: These results show that these T cells are potent CTLs that are able to effectively lyse myeloma cells but not normal blood cells and also suggest that Hsps from allogeneic tumor cells may be used as vaccines to immunize patients.

Antigens, Neoplasm↗
PubMed2005

Tumor evasion of the immune system: inhibiting p38 MAPK signaling restores the function of dendritic cells in multiple myeloma.

Dendritic cells (DCs) from patients with cancer are functionally defective, but the molecular mechanisms underlying these defects are poorly understood. In this study, we used the murine 5TGM1 myeloma model to examine the effects and mechanisms of tumor-derived factors on the differentiation and function of DCs. Myeloma cells or tumor culture conditioning medium (TCCM) were shown to inhibit the differentiation and function of BM-derived DCs (BMDCs), as evidenced by the down-regulated expression of DC-related surface molecules, decreased IL-12, and compromised capacity of the cells to activate allospecific T cells. Moreover, TCCM-treated BMDCs were inferior to normal BMDCs at priming tumor-specific immune responses in vivo. Neutralizing antibodies against IL-6, IL-10, and TGF-beta partially abrogated the effects. TCCM treatment activated p38 mitogen-activated protein kinase (MAPK) and Janus kinase (JNK) but inhibited extracellular regulated kinase (ERK). Inhibiting p38 MAPK restored the phenotype, cytokine secretion, and function of TCCM-treated BMDCs. BMDCs from cultures with TCCM and p38 inhibitor was as efficacious as normal BMDCs at inducing tumor-specific antibody, type 1 T cell, and cytotoxic T lymphocyte (CTL) responses and at prolonging mouse survival. Thus, our results suggested that tumor-induced p38 MAPK activation and ERK inhibition in DCs may be a new mechanism for tumor evasion and that regulating these pathways during DC differentiation provides new strategies for generating potent DC vaccines for immunotherapy in patients with cancer.

Animals↗
PubMed2005

Critical roles of Raf/MEK/ERK and PI3K/AKT signaling and inactivation of p38 MAP kinase in the differentiation and survival of monocyte-derived immature dendritic cells.

OBJECTIVE: The aim of this study is to investigate the signaling pathways and their roles in the differentiation of immature monocyte-derived dendritic cells (MoDCs). METHODS: MoDCs were generated from peripheral blood monocytes (PBMCs) using the standard protocols. Various kinase inhibitors, including SB203580, PD98059, and LY294002 and Wortmannin, or p38 activator were added at the beginning of the cultures. After 7 days of culture, immature MoDCs were harvested and analyzed for their surface expression of relevant molecules and the fraction of apoptotic cells by flow cytometry. Western blots were used to analyze mitogen-activated protein kinase (MAPK), NF-kappaB, Raf, mitogen-induced extracellular kinase (MEK), and AKT expression by cultured cells. NF-kappaB was also analyzed by electrophoretic mobility shift assay. Allogeneic MLR was used to examine the capacity of MoDCs to activate allogeneic T cells. RESULTS: The present study shows that the differentiation of immature MoDCs was accompanied by phosphorylation of AKT, Raf, MEK, extracellular signal-related kinase (ERK), and NF-kappaB activity. Inhibiting PI3K or MEK retarded the differentiation of immature MoDCs and induced apoptosis in 10 to 30% of the cultured cells, while inhibiting both PI3K and MEK resulted in apoptosis in 70% of the cells. Surprisingly, inhibiting p38 enhanced the phosphorylation of ERK and NF-kappaB activity and led to an enhanced upregulation, compared with control cells, of expression of dendritic cell (DC)-related adhesion and costimulatory molecules and antigen presentation capacity. CONCLUSIONS: Our results indicate that the Raf/MEK/ERK and PI3K/AKT signaling pathways play critical roles in the differentiation and survival of immature MoDCs. Moreover, this study also demonstrates that activated p38 is detrimental to the differentiation of immature MoDCs.

Anisomycin↗
PubMed2004

Cancer and the microenvironment: myeloma-osteoclast interactions as a model.

We have investigated the interaction between tumor cells and specific cells in their microenvironment using myeloma as a model. The role of myeloma-induced osteoclastogenesis in the disease was studied ex vivo. Myeloma plasma cells freshly purified from patients' bone marrow attracted committed osteoclast (OC) precursors (n = 9; P < 0.01) and in 22 experiments directly induced their differentiation to multinucleated, bone-resorbing OCs (P < 0.00002) in a receptor activator of nuclear factor-kappaB ligand-mediated mechanism that was inhibited by the receptor activator of nuclear factor-kappaB (RANK-Fc) in 13 experiments by 71 +/- 12% (P < 0.008). In contrast, myeloma cells did not induce differentiation of peripheral blood mononuclear cells. Myeloma plasma cells cocultured with OCs retained their viability and proliferative activity for >13 weeks. After 14 days in coculture, the plasma cells from 29 patients had higher viability (P < 2 x 10(-6)), fewer apoptotic cells (P < 4 x 10(-15)), and a higher bromodeoxyuridine labeling index (P < 0.0006) than controls. Physical contact between OCs and myeloma cells was required for these effects to take place. No differences were observed between OCs from healthy donors and those from myeloma patients. Blocking interleukin 6 activity, while reducing survival of myeloma cells, had no effect on their proliferative activity. These results support data obtained from animal models and clinical observations on the essential role of the microenvironment in tumor sustenance and progression.

Annexin A5↗
PubMed2004

Post-traumatic endophthalmitis.

OBJECTIVE: To establish risk factors for the occurrence of post-traumatic endophthalmitis, to observe the efficacy of prophylaxis, and to describe the clinical features of post-traumatic endophthalmitis. DESIGN: Partially prospective consecutive case-control study. PARTICIPANTS: A total of 250 consecutive patients admitted to a single ophthalmic hospital with open globe injuries during a 3-year period were included. METHODS: Patients with post-traumatic endophthalmitis were identified prospectively and added to an endophthalmitis database. All open globe injuries during the same time period were identified through a retrospective search of inpatient admissions, and their charts were reviewed. Information collected from all patient files included patient age; gender; injury setting (indoor/outdoor); wound contamination; nature of injury (site on eye, lens involvement, retained intraocular foreign body); mechanism of injury (penetration/perforation/rupture/ruptured surgical wound); prophylactic antibiotic administration, including route and timing; timing of primary repair; lensectomy at the time of primary repair; and depot corticosteroid at the time of primary repair. Any association between these parameters and the subsequent development of endophthalmitis was investigated. Any association between endophthalmitis and final visual acuity (VA) and also enucleation was evaluated. MAIN OUTCOME MEASURE: Development of endophthalmitis. RESULTS: The frequency of endophthalmitis after open globe injury was 6.8%. The following factors were associated with the subsequent development of endophthalmitis by univariate analysis: dirty wound (14.3% vs. 4.1%, P = 0.01), retained intraocular foreign body (13.0% vs. 4.4%, P = 0.02), lens capsule breach (12.8% vs. 3.2%, P = 0.01), delayed primary repair (> or =12 hours) (11.3% vs. 2.9%, P = 0.02), and rural address (10.1% vs. 4.3%, P = 0.07). Risk factors identified after multivariate analysis were dirty injury (odds ratio [OR], 5.3; 95% confidence interval [CI)], 1.5-18.7), breach of lens capsule (OR, 4.4; 95% CI, 1.2-15.6), and delay in primary repair (per hour: OR, 1.013; 95% CI, 1.002-1.024). None of the following factors was found to be associated with post-traumatic endophthalmitis: patient age, gender, injury setting, site of injury on eye, mechanism of injury, antibiotic administration, lensectomy at the time of primary repair, and depot corticosteroid at the time of primary repair. Final VA tended to be worse in eyes with endophthalmitis (P = 0.08). Endophthalmitis did not significantly influence the frequency of enucleation/evisceration (5.9% vs. 4.3%, P = 0.55). CONCLUSIONS: Delay in primary repair, ruptured lens capsule, and dirty wound were each independently associated with the development of post-traumatic endophthalmitis. Patients with > or =2 of these 3 risk factors had a particularly high frequency of infection.

Adolescent↗
PubMed2003

Novel and detrimental effects of lipopolysaccharide on in vitro generation of immature dendritic cells: involvement of mitogen-activated protein kinase p38.

Dendritic cells (DCs) are recognized as major players in the regulation of immune responses to a variety of Ags, including bacterial agents. LPS, a Gram-negative bacterial cell wall component, has been shown to fully activate DCs both in vitro and in vivo. LPS-induced DC maturation involves activation of p38, extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases, and NF-kappaB. Blocking p38 inhibits LPS-induced maturation of DCs. In this study we investigated the role of LPS in the in vitro generation of immature DCs. We report here that in contrast to the observed beneficial effects on DCs, the presence of LPS in monocyte culture retarded the generation of immature DCs. LPS not only impaired the morphology and reduced the yields of the cultured cells, but also inhibited the up-regulation of surface expression of CD1a, costimulatory and adhesion molecules. Furthermore, LPS up-regulated the secretion of IL-1beta, IL-6, IL-8, IL-10, and TNF-alpha; reduced Ag presentation capacity; and inhibited phosphorylation of ERK, but activated p38, leading to a reduced NF-kappaB activity in treated cells. Neutralizing Ab against IL-10, but not other cytokines, partially blocked the effects of LPS. Inhibiting p38 (by inhibitor SB203580) restored the morphology, phenotype, and Ag presentation capacity of LPS-treated cells. SB203580 also inhibited LPS-induced production of IL-1beta, IL-10, and TNF-alpha; enhanced IL-12 production; and recovered the activity of ERK and NF-kappaB. Thus, our study reveals that LPS has dual effects on DCs that are biologically important: activating existing DCs to initiate an immune response, and inhibiting the generation of new DCs to limit such a response.

Cell Differentiation↗
PubMed2003

Beta 2-microglobulin as a negative regulator of the immune system: high concentrations of the protein inhibit in vitro generation of functional dendritic cells.

Two common features in human immunodeficiency virus infection and acquired immunodeficiency syndrome, rheumatoid arthritis, and hematologic malignancies including multiple myeloma are elevated serum levels of beta(2)-microglobulin (beta(2)M) and activation or inhibition of the immune system. We hypothesized that beta(2)M at high concentrations may have a negative impact on the immune system. In this study, we examined the effects of beta(2)M on monocyte-derived dendritic cells (MoDCs). The addition of beta(2)M (more than 10 microg/mL) to the cultures reduced cell yield, inhibited the up-regulation of surface expression of human histocompatibility leukocyte antigen (HLA)-ABC, CD1a, and CD80, diminished their ability to activate T cells, and compromised generation of the type-1 T-cell response induced in allogeneic mixed-lymphocyte reaction. Compared with control MoDCs, beta(2)M-treated cells produced more interleukin-6 (IL-6), IL-8, and IL-10. beta(2)M-treated cells expressed significantly fewer surface CD83, HLA-ABC, costimulatory molecules, and adhesion molecules and were less potent at stimulating allospecific T cells after an additional 48-hour culture in the presence of tumor necrosis factor-alpha and IL-1beta. During cell culture, beta(2)M down-regulated the expression of phosphorylated mitogen-activated protein (MAP) kinases, extracellular signal-related kinase (ERK), and mitogen-induced extracellular kinase (MEK), inhibited nuclear factor-kappaB (NF-kappaB), and activated signal transducer and activator of transcription-3 (STAT3) in treated cells, all of which are involved in cell differentiation and proliferation. Thus, our study demonstrates that beta(2)M at high concentrations retards the generation of MoDCs, which may involve down-regulation of major histocompatibility complex class I molecules, inactivation of Raf/MEK/ERK cascade and NF-kappaB, and activation of STAT3, and it merits further study to elucidate the underlying mechanisms.

Antigens, CD↗
PubMed2003

Clinical outcomes following laser photocoagulation treatment for diabetic retinopathy at a large Australian ophthalmic hospital.

OBJECTIVE: To evaluate clinical outcomes of diabetic retinopathy laser treatment at a large Australian ophthalmic hospital. METHODS: A retrospective medical record review of all patients who had initial laser treatment for diabetic retinopathy at the Royal Victorian Eye and Ear Hospital from January 1997 to December 1998. RESULTS: The study included 322 eyes from 203 patients. The mean age was 65.8 years (range 18-89) and the mean follow up was 18 months (range 2-33). Focal photocoagulation treatment alone was performed in 238 eyes. Clinically significant macular oedema (CSME) resolved in 218 (91.6%) eyes. Vision was improved or maintained in 137 (57.6%) eyes. Moderate visual loss occurred in 49 (20.6%) eyes. Panretinal photocoagulation (PRP) was performed in 84 eyes, including 37 eyes with PRP alone and 47 eyes with PRP and focal together. Neovascularization regressed in 55 (65.5%) eyes. Vision was improved or maintained in 52 (61.9%) eyes. Moderate visual loss was observed in 20 (23.8%) eyes and severe visual loss was observed in 4 (4.8%) eyes. CONCLUSIONS: The clinical outcomes reported here are similar to those reported in other studies.

Adolescent↗
PubMed2003

Dendritic cell-based immunotherapy in multiple myeloma.

Most patients with multiple myeloma (MM) cannot be cured with currently available therapies. Although complete remission could be achieved in about 50% of newly diagnosed patients with high-dose chemotherapy and tandem transplantation, relapses of the underlying disease occur frequently. To realize long-term disease-free survival, it will be necessary to develop complementary therapies that are non-cross-resistant with chemotherapy. To this end, immunotherapy aimed at inducing or enhancing tumor-specific immunity that may control or eradicate remaining tumor cells may be an appealing method. Dendritic cells (DCs) are professional antigen-presenting cells and considered the best natural adjuvants for immunotherapy in malignancies. Vaccination with tumor antigen-pulsed DCs has been shown to be protective and therapeutic in animal tumor models, and induced a strong tumor-specific immunity and durable tumor regression in human solid tumors and B-cell lymphoma. As a result, clinical trials in various human malignancies have been initiated. This review will focus on DC-based immunotherapy in MM. I will discuss myeloma antigens and antigen-specific immune responses, the capacity of DCs to present myeloma antigens and induce cytotoxic T-cell responses, and clinical experience of DC vaccination in myeloma patients.

Antigen-Presenting Cells↗
PubMed2003

a-Stratified CAT design with content blocking.

Content balancing is often required in the development and implementation of computerized adaptive tests (CATs). In the current study, we propose a modified a-stratified method, the a-stratified method with content blocking. As a further refinement of a-stratified CAT designs, the new method incorporates content specifications into item pool stratification. Simulation studies were conducted to compare the new method with three previous item selection methods: the a-stratified method; the a-stratified with b-blocking method; and the maximum Fisher information method with Sympson-Hetter exposure control. The results indicated that the refined a-stratified design performed well in reducing item overexposure rates, balancing item usage within the pool, and maintaining measurement precision, in a situation where all four procedures were forced to balance content.

Data Interpretation, Statistical↗
PubMed2003

Immunotherapy in multiple myeloma: current strategies and future prospects.

Multiple myeloma is still a fatal disease. Despite advances in high-dose chemotherapy supported by autologous transplantations, relapse of the underlying disease remains the primary cause of treatment failure. Strategies for post-transplantation immunomodulation would be desirable for eradication of remaining tumor cells. Toward this end, immunotherapy aimed at inducing myeloma-specific immunity in patients has been exploited. Idiotype protein, secreted by myeloma cells, has been the main target for immunotherapy as it is the best-defined, tumor-specific antigen. The focus of this review article is the use of idiotype as a form of protein antigen to immunize patients, to load dendritic cells, or as part of DNA vaccines. Various strategies of immunotherapy and the outcome of clinical trials are also discussed.

Antigen Presentation↗
PubMed2003

Transforming and secreting expression of human egf in mutant strain WYBS2001 of Bacillus and its functions.

Mutant strain WYBS2001 of B. subtilis with strong anti-pathogenic activity was obtained by mutagenic ultraviolet rays. The gene fragment of Human Epidermal Growth Factor(hegf) of 175 bp was synthesized by PCR and the restriction sites Pst I and Hind III, original code and the signal sequence CTTAGA of secreting vector pUS186 were induced in the fragment. The DNA sequencing result revealed that the synthesized fragment was identical with that of human egf. Then the biological engineering strain WYBS2001T with human egf was obtained by transforming pUSE which was constructed by cloning egf into the secreting plasmid pUS186, into mutant strain WYBS2001. The result of RIA showed that hEGF can be found in the supernatant of the cultures and its content was 7.6 ng/ml. And the content can be increased if the proteinase inhibitor was added into the medium. After several generations' culturing, WYBS2001T positive engineering strain can still secrete and express hEGF steadily. The result of experiment showed hEGF had biological activity of proliferation and growth of human cell K562 in vitro. WYBS2001T engineering strain had obvious effect on healing the burned animals' models. This research showed microecological gene-engineering bacteria has good applying foreground.

Amino Acid Sequence↗
PubMed2002

Tumor lysate-specific cytotoxic T lymphocytes in multiple myeloma: promising effector cells for immunotherapy.

The idiotype protein, secreted by myeloma plasma cells, is a tumor-specific but weak antigen. Idiotype-based immunotherapy has been explored in myeloma patients with disappointing results. It is conceivable that myeloma cells contain a multitude of tumor antigens that can more effectively stimulate antitumor T cells. To explore the possibility of using whole myeloma cells as a source of tumor antigens for immunotherapy, the current study was undertaken to generate and examine the function of myeloma-specific cytotoxic T lymphocytes (CTLs) by using dendritic cells (DCs) pulsed with myeloma cell lysates as stimulating cells. After repeated stimulation, specific CTL lines, containing CD4(+) and CD8(+) T cells, were generated from myeloma patients. Our results show that these T cells not only recognized and lysed autologous myeloma protein-pulsed DCs, they also killed autologous primary myeloma cells. Occasionally, CTLs responded to autologous idiotype-pulsed DCs and to allogeneic primary myeloma cells. No cytolytic activity, however, was detected against autologous lymphocytes including B cells, suggesting that the T cells acted specifically against myeloma cells. Cytotoxicity against target cells was major histocompatibility complex class 1 and, to a lesser extent, class 2 restricted and was dependent mainly on the perforin-mediated pathway. CTLs secreted predominantly interferon-gamma and tumor necrosis factor-alpha on antigenic stimulation, indicating a type 1 T-cell subset. These findings represent the first demonstration that tumor cell lysate-primed CTLs kill only myeloma cells, not autologous lymphocytes. This provides a rationale for myeloma cell-based immunotherapy in multiple myeloma.

Antigen Presentation↗