Publications by authors named "Minzhen Xu"

Follicular tracking is typically conducted using ultrasound technology, but its effectiveness is constrained by limited resolution. High-resolution imaging of deep tissues can be accomplished using luminescence imaging in the near-infrared II window (NIR-II, 1000-1700 nm); however, the contrast agents that are used lack specificity. Here, it is reported that the FDA-approved indocyanine green (ICG)-conjugated recombinant human chorionic gonadotropin (hCG) protein can target early follicles with long-term effectiveness.

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Background: Polycystic ovary syndrome (PCOS) affects 8%-15% of reproductive-age women and is associated with reproductive disorders, abdominal obesity, hyperinsulinemia, insulin resistance, type 2 diabetes, and cardiovascular diseases. Acupuncture, as a traditional physical therapy method, could affect various metabolic disorders such as obesity, hyperplasia, gout, and cardiovascular and cerebrovascular diseases in clinical practice. Moreover, electroacupuncture (EA) has been shown to decrease body weight in rats with PCOS; however, the mechanism of weight loss and the relationship between adipose tissue and gut microbiota remain unclear.

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Active immunotherapy is becoming a reality in the treatment of malignancies. Peptide-based vaccines represent a simple, safe, and economic basis for cancer immunotherapeutics development. However, therapeutic efficacy has been disappointing.

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Activation of antigen-specific CD4+ T cells is critical for vaccine design. We have advanced a novel technology for enhancing activation of antigen-specific CD4+ T helper cells whereby a fragment of the MHC class II-associated invariant chain (Ii-Key) is linked to an MHC class II epitope. An HLA-DR4-restricted HPV16 E7 epitope, HPV16 E7(8-22), was used to create a homologous series of Ii-Key/HPV16 E7 hybrids testing the influence of spacer length on in vivo enhancement of HPV16 E7(8-22)-specific CD4+ T lymphocyte responses.

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HLA-DM (DM) plays a critical role in Ag presentation to CD4 T cells by catalyzing the exchange of peptides bound to MHC class II molecules. It is known that DM interaction with MHC II involves conformational changes in the MHC II molecule leading to the disturbance of H-bonds formed between the bound peptide and the MHC II groove leading to peptide dissociation. The specific region of the DM molecule that induces this peptide dissociation is not defined.

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Life-threatening diseases, such as cancer and pandemic influenza, demand new efforts towards effective vaccine design. Peptides represent a simple, safe and adaptable basis for vaccine development; however, the potency of peptide vaccines is insufficient in most cases for significant therapeutic efficacy. Several methods, such as Ligand Epitope Antigen Presentation System and ISCOMATRIX, have been developed to enhance the potency of peptide vaccines.

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Summary One function of the major histocompatibility complex (MHC) class II-associated invariant chain (Ii) is to prevent MHC class II molecules from binding endogenously generated antigenic epitopes. Ii inhibition leads to MHC class II presentation of endogenous antigens by APC without interrupting MHC class I presentation. We present data that in vivo immunization of BALB/c mice with HIV gp120 cDNA plus an Ii suppressive construct significantly enhances the activation of both gp120-specific T helper (Th) cells and cytotoxic T lymphocytes (CTL).

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The general principle for tumor cells to escape from immune surveillance is to prevent tumor antigens from being recognized by the immune system. Many methods have been developed to increase the immunogenecity of the tumor cells. The most efficient methods are able to force tumor cells to present their own tumor antigens to the immune system.

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Potent MHC class II antigenic peptide vaccines are created by covalently linking the N-terminus of a MHC class II epitope through a polymethylene bridge to the C-terminus of the Ii-Key segment of the Ii protein. Such hybrids enhance potency of presentation in vitro of the MHC class II epitope about 200 times relative to the epitope-only peptide. In vivo, as measured by IFN-gamma ELISPOT assays, the helper T cell response to vaccination is enhanced up to 8 times.

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Linking the Ii-Key functional group LRMK, through a simple polymethylene linker, to the melanoma gp100(48-58) MHC class II epitope significantly enhances the vaccine response to that epitope in DR4-IE transgenic mice. A homologous series of Ii-Key/gp100(46-58) hybrids was synthesized to test the influence of spacer length (between Ii-Key and the gp100(48-58) epitope) on in vivo enhancement of gp100(48-58)-specific CD4+ T-lymphocyte responses. As measured by IFN-gamma and IL-4 ELISPOT cytokine assays, the most effective vaccine hybrid was the one with a shorter linker between Ii-Key and the epitope.

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Transfecting genes into tumors, to upregulate major histocompatibility complex (MHC) class I and class II molecules and inhibit MHC class II associated invariant chain (Ii), induces a potent anti-tumor immune response when preceded by tumor irradiation, in murine RM-9 prostate carcinoma. The transfected genes are cDNA plasmids for interferon-gamma (pIFN-gamma), MHC class II transactivator (pCIITA), an Ii reverse gene construct (pIi-RGC), and a subtherapeutic dose of adjuvant IL-2 (pIL-2). Responding mice rejected challenge with parental tumor and demonstrated tumor-specific cytotoxic T lymphocytes (CTLs).

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Linkage of the Ii-Key segment of the Ii protein to MHC class II epitope gp100(46-58) using a polymethylene linker significantly enhances the production of epitope-specific antibodies in HLA-DR4-IE transgenic mice. This enhancement is not restricted by the spacer length in between the Ii-Key and epitope. The use of either IFA or CFA induced only epitope-specific IgG1.

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Ii protein suppression is a promising antisense drug-based therapy that dramatically enhances the immunogenicity of tumor cell major histocompatibility complex class II-presented antigenic epitopes. The strength of this approach is that the antisense only needs to be transiently effective in a fraction of the tumor cells. The systemic antitumor immune response generated subsequently eradicates both directly treated cells and distant tumor deposits.

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Immunological control or cure of tumors depends on initiating a robust T helper cell response to MHC class II epitopes of tumor-associated antigens. T helper cells regulate the potency of cytotoxic T lymphocyte and antibody responses. We have developed a novel approach to stimulate T helper cells by converting tumor cells into MHC class II molecule-positive, antigen presenting cells.

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Purpose: Cytotoxic T lymphocytes (CTL)- and T-helper cell-specific, and major histocompatibility complex (MHC) class-I and class-II peptides, respectively, of the HER-2/ neu protein, induce immune responses in patients. A major challenge in developing cancer peptide vaccines is breaking tolerance to tumor-associated antigens which are functionally self-proteins. An adequate CD4+ T-helper response is required for effective and lasting responses.

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The Ii-Key/MHC class II epitope hybrid acts on MHC class II molecules to facilitate replacement of antigenic peptides with the epitope tethered to the Ii-Key motif. Hybrid peptides linking an immunoregulatory segment of the Ii protein (Ii-Key peptide) through a polymethylene bridge to MHC class II epitopes of HIV gp160 or gag are potent vaccines to elicit CD4(+) T cell responses. More potent responses to two MHC class II epitopes, HIV gp160(843-852) or HIV gag(279-292), occurred in mice immunized with Ii-Key hybrid peptides than with epitope-only peptides, as measured in IL-4 and IFN-gamma ELISPOT assays of splenic lymphocytes stimulated in vitro by epitope-only peptides.

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A potent antitumor CD4(+) T-helper cell immune response is created by inducing tumor cells in vivo to a MHC class II(+)/Ii(- )phenotype. MHC class II and Ii molecules were induced in tumor cells in situ following tumor injection of a plasmid containing the gene for the MHC class II transactivator (CIITA). Ii protein was suppressed by the antisense effect of an Ii-reverse gene construct (Ii-RGC) in the same or another co-injected plasmid.

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Our goal was to convert murine RM-9 prostate carcinoma cells in vivo into antigen-presenting cells capable of presenting endogenous tumor antigens and triggering a potent T-helper cell-mediated immune response essential for the generation of a specific antitumor response. We showed that generating the major histocompatibility complex (MHC) class I+/class II+/Ii- phenotype, within an established subcutaneous RM-9 tumor nodule, led to an effective immune response limiting tumor growth. This phenotype was created by intratumoral injection of plasmid cDNAs coding for interferon gamma, MHC class II transactivator, and an antisense reverse gene construct (RGC) for a segment of the gene for Ii protein (-92,97).

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