Biomedical subjects

Bruce E Loveland

Publications and source records attributed to Bruce E Loveland.

10 recordsLinked to original sources

PubMed2006

Pilot phase III immunotherapy study in early-stage breast cancer patients using oxidized mannan-MUC1 [ISRCTN71711835].

INTRODUCTION: Mucin 1 (MUC1) is a high molecular weight glycoprotein overexpressed on adenocarcinoma cells and is a target for immunotherapy protocols. To date, clinical trials against MUC1 have included advanced cancer patients. Herein, we report a trial using early stage breast cancer patients and injection of oxidized mannan-MUC1. METHOD: In a randomized, double-blind study, 31 patients with stage II breast cancer and with no evidence of disease received subcutaneous injections of either placebo or oxidized mannan-MUC1, to immunize against MUC1 and prevent cancer reoccurrence/metastases. Twenty-eight patients received the full course of injections of either oxidized mannan-MUC1 or placebo. Survival and immunological assays were assessed. RESULTS: After more than 5.5 years had elapsed since the last patient began treatment (8.5 years from the start of treatment of the first patient), the recurrence rate in patients receiving the placebo was 27% (4/15; the expected rate of recurrence in stage II breast cancer); those receiving immunotherapy had no recurrences (0/16), and this finding was statistically significant (P = 0.0292). Of the patients receiving oxidized mannan-MUC1, nine out of 13 had measurable antibodies to MUC1 and four out of 10 had MUC1-specific T cell responses; none of the placebo-treated patients exhibited an immune response to MUC1. CONCLUSION: The results suggest that, in early breast cancer, MUC1 immunotherapy is beneficial, and that a larger phase III study should be undertaken.

Adenocarcinoma↗

PubMed2006

Mannan-MUC1-pulsed dendritic cell immunotherapy: a phase I trial in patients with adenocarcinoma.

PURPOSE: Tumor antigen-loaded dendritic cells show promise for cancer immunotherapy. This phase I study evaluated immunization with autologous dendritic cells pulsed with mannan-MUC1 fusion protein (MFP) to treat patients with advanced malignancy. EXPERIMENTAL DESIGN: Eligible patients had adenocarcinoma expressing MUC1, were of performance status 0 to 1, with no autoimmune disease. Patients underwent leukapheresis to generate dendritic cells by culture ex vivo with granulocyte macrophage colony-stimulating factor and interleukin 4 for 5 days. Dendritic cells were then pulsed overnight with MFP and harvested for reinjection. Patients underwent three cycles of leukapheresis and reinjection at monthly intervals. Patients with clinical benefit were able to continue with dendritic cell-MFP immunotherapy. RESULTS: Ten patients with a range of tumor types were enrolled, with median age of 60 years (range, 33-70 years); eight patients were of performance status 0 and two of performance status 1. Dendritic cell-MFP therapy led to strong T-cell IFNgamma Elispot responses to the vaccine and delayed-type hypersensitivity responses at injection sites in nine patients who completed treatments. Immune responses were sustained at 1 year in monitored patients. Antibody responses were seen in three patients only and were of low titer. Side effects were grade 1 only. Two patients with clearly progressive disease (ovarian and renal carcinoma) at entry were stable after initial therapy and went on to further leukapheresis and dendritic cell-MFP immunotherapy. These two patients have now each completed over 3 years of treatment. CONCLUSIONS: Immunization produced T-cell responses in all patients with evidence of tumor stabilization in 2 of the 10 advanced cancer patients treated. These data support further clinical evaluation of this dendritic cell-MFP immunotherapy.

Adenocarcinoma↗

PubMed2006

Delivery of tumor associated antigens to antigen presenting cells using penetratin induces potent immune responses.

Cytoplasmic delivery of proteins or CTL epitopes is crucial for the presentation of antigen for the generation of CTL. We previously described the use of the 16-amino acid peptide penetratin from the Drosophila Antennapedia domain (Int) to transport CTL epitopes into cells. Here we show that, Int, incorporating MUC1 CTL epitopes in tandem is able to facilitate their rapid uptake by macrophages and dendritic cells (DC) in an energy-dependent endocytic pathway. We also demonstrate for the first time that Int conjugated proteins are also able to be efficiently taken up by DC. Furthermore, C57BL/6 and HLA-A2 transgenic mice immunized with the Int-peptides or Int-proteins induce strong IFN-gamma secreting T cells and weak IgG1 antibodies. Immunized C57BL/6 mice were protected against the growth of a MUC1(+) tumor cell line.

Animals↗

PubMed2004

Characterization of a CD46 transgenic pig and protection of transgenic kidneys against hyperacute rejection in non-immunosuppressed baboons.

Human membrane cofactor protein (CD46) controls complement activation and when expressed sufficiently as a transgene protects xenografts against complement-mediated rejection, as shown here using non-immunosuppressed baboons and heterotopic CD46 transgenic pig kidney xenografts. This report is of a carefully engineered transgene that enables high-level CD46 expression. A novel CD46 minigene was validated by transfection and production of a transgenic pig line. Pig lymphocytes were tested for resistance to antibody and complement-mediated lysis, transgenic tissues were characterized for CD46 expression, and kidneys were transplanted to baboons without immunosuppression. Absorption of anti-Galalpha(1,3)Gal epitope (anti-GAL) serum antibodies was measured. Transgenic pigs expressed high levels of CD46 in all tissues, especially vascular endothelium, with stable expression through three generations that was readily monitored by flow cytometry of transgenic peripheral blood mononuclear cells (PBMC). Transgenic PBMC pre-sensitized with antibody were highly resistant to human complement-mediated lysis which readily lysed normal pig PBMC. Normal pig kidneys transplanted without cold ischemia into non-immunosuppressed adult baboons survived a median of 3.5 h (n = 7) whereas transgenic grafts (n = 9), harvested at approximately 24-h intervals, were either macroscopically normal (at 29, 48 and 68 h) or showed limited macroscopic damage (median > 50 h). Microscopic assessment of transplanted transgenic kidneys showed only focal tubular infarcts with viable renal tissue elsewhere, no endothelial swelling or polymorph adherence and infiltration by lymphocytes beginning at 3 days. Coagulopathy was not a feature of the histology in four kidneys not rejected and assessed at 48 h or later after transplantation. Baboon anti-GAL serum antibody titers were high before transplantation and, in one extensively analyzed recipient, reduced approximately 8-fold within 5.5 h. The data demonstrate that a single CD46 transgene controls hyperacute kidney graft rejection in untreated baboons despite the presence of antibody and complement deposition. The expression levels, tissue distribution and in vitro functional tests indicate highly efficient CD46 function, controlling both classical and alternative pathway complement activation, which suggests it might be the complement regulator of choice to protect xenografts.

Acute Disease↗

PubMed2004

Novel role for decay-accelerating factor in coxsackievirus A21-mediated cell infectivity.

Decay-accelerating factor (DAF) is involved in the cell membrane attachment of many human enteroviruses. Presently, further specific active roles of DAF in mediating productive cell infection and in the pathogenesis of natural enterovirus infection are poorly understood. In an attempt to more fully understand the role of DAF in lytic cell infection we examined the specific interactions of the prototype strain of coxsackievirus A21 (CVA21) with surface-expressed DAF. Investigations into discrete DAF-CVA21 interactions focused on viral binding; viral particle elution with respect to the parameters of time, temperature, and pH; and subsequent cell infection. Radiolabeled-virus binding assays revealed that peak elution of CVA21 from DAF occurred within 15 min of initial attachment and that the DAF-eluted virus increased in a linear fashion with respect to temperature and pH. CVA21 eluted from endogenous surface-expressed DAF was highly infectious, in contrast to CVA21 eluted from intercellular adhesion molecule 1 (ICAM-1), which retained little to no infectivity. Using an adenovirus transduction system, we demonstrate that CVA21 can remain infectious for up to 24 h after DAF binding and is capable of initiating a multicycle lytic infection upon delayed ICAM-1 surface expression. Taken together, the data suggest that a major role of DAF in cell infection by the prototype strain of CVA21 is to provide membrane concentration of infectious virions, effectively increasing viral interactions with endogenous or induced ICAM-1.

Animals↗

PubMed2003

Ligand binding determines whether CD46 is internalized by clathrin-coated pits or macropinocytosis.

CD46 is a ubiquitous human cell surface receptor for the complement components C3b and C4b and for various pathogens, including the measles virus and human herpes virus 6. Ligand binding to CD46 affects (i) protection of autologous cells from complement attack by breakdown of complement components, (ii) intracellular signals that affect the regulation of immune cell function, (iii) antigen presentation, and (iv) down-regulation of cell surface CD46. Recent evidence indicates that CD46 signaling can link innate and acquired immune function. The molecular mechanisms for these processes and the importance of intracellular trafficking of the receptor have not yet been elucidated. We demonstrate here that, in nonlymphoid cells, CD46 is constitutively internalized via clathrin-coated pits, traffics to multivesicular bodies, and is recycled to the cell surface. However, cross-linking of CD46 at the cell surface, by either multivalent antibody or by measles virus, induces pseudopodia that engulf the ligand in a process similar to macropinocytosis, and leads to the degradation of cell surface CD46. Thus, we have elucidated two pathways for CD46 internalization, which are regulated by the valence of cross-linking of CD46 and which utilize either clathrin-coated pits or pseudopodial extension. This has important implications for CD46 signaling, antigen presentation, CD46 down-regulation, and engulfment of pathogens.

Antibodies↗

PubMed2003

CD46 protects pig islets from antibody but not cell-mediated destruction in the mouse.

We have previously reported that islets present in cultured fetal pig pancreas (FPP) are resistant to destruction by Galalpha(1,3)Gal antibodies and compliment, but are susceptible to the 'secondary' antibody response which occurs on transplanting pig islet tissue to Galo/o murine recipients. In a model of antibody-mediated graft rejection, we tested the resistance of porcine islets to antibody. Using FPP from human CD46 transgenic pigs, we now report that the complement regulator, CD46, affords protection from antibody-mediated rejection when mouse anti-pig serum (MAPS) was administered to scid mice bearing PFF grafts from either CD46 transgenic or normal pigs. Indeed, whereas normal pig islets were destroyed by an intraperitoneal (i.p.) injection of 0.1 to 0.2 ml of MAPS antibody, destruction of CD46-expressing transgenic islets required 0.5 ml, i.e. up to five times the amount. In contrast, there was no prolongation of the survival of CD46 transgenic mouse skin or heart major histocompatibility complex-compatible or -incompatible allografts--rejected by predominantly cellular immune mechanisms, as opposed to xenograft rejection. Although complement regulators have been examined for their protective role in hyperacute rejection of vascularized xenografts, it is clear that they also have protective effects in the later, antibody-mediated responses, but are unlikely to effect the inflammatory response in cell-mediated rejection.

Animals↗

PubMed2003

Aspects of cancer immunotherapy.

Cancer immunotherapy has traditionally undergone a 'revolution' every decade, from the use of Bacille Calmette-Guérin by scarification in the 1970s, to interleukin-2 therapies in the 1980s, and monoclonal antibody treatments in the early 1990s. Usually the early reports on the use of such agents were encouraging, but when more patients were studied in multiple centres, the initial promising results could not be confirmed. Now in a new century, we have more reagents and methods available than ever before - indeed, with such a plethora of reagents it is difficult to envisage them being fully and appropriately tested within the next decade, by which time there will be even more reagents to test. However, there have been three major advances which should lead to substantial progress in cancer immunotherapy: (1) the widespread use of genetic engineering, enabling identification of candidate vaccine proteins and manipulation of their sequences; (2) the production of antigens, antibodies and cytokines in large amounts by recombinant technologies, and (3) an understanding of the mode of presentation of peptides by major histocompatibility complex Class I and Class II molecules and their recognition by T cells. Despite these advances, there are major problems facing cancer immunotherapy, such as the ability of tumours to mutate and evade the immune system and the difficulty of precisely defining the interactions of effector cells in mediating 'rejection' or destruction of a tumour. There are clearly immunological similarities with diseases such as malaria and schistosomiasis, where the invading foreign organisms can use a variety of strategies to resist an elicited immune response. The failure to find a suitable vaccine for these diseases must lead to some pessimism for the development of immunotherapy for an autologous tumour. However, there are promising studies now in progress which should give an indication of the most important directions to follow. This review provides a commentary on aspects of cancer immunotherapy and in particular will deal with: (1) the selection of antigens as vaccine components; (2) the modes of presentation of antigens, particularly by major histocompatibility complex Class I molecules; and (3) new modes of delivery of vaccine immunogens.

Antigen Presentation↗

PubMed2002

Identification of the streptococcal M protein binding site on membrane cofactor protein (CD46).

Adherence of group A streptococcus (GAS) to keratinocytes is mediated by an interaction between human CD46 (membrane cofactor protein) with streptococcal cell surface M protein. CD46 belongs to a family of proteins that contain structurally related short consensus repeat (SCR) domains and regulate the activation of the complement components C3b and/or C4b. CD46 possesses four SCR domains and the aim of this study was to characterize their interaction with M protein. Following confirmation of the M6 protein-dependent interaction between GAS and human keratinocytes, we demonstrated that M6 protein binds soluble recombinant CD46 protein and to a CD46 construct containing only SCRs 3 and 4. M6 protein did not bind to soluble recombinant CD46 chimeric proteins that had the third and/or fourth SCR domains replaced with the corresponding domains from another complement regulator, CD55 (decay-accelerating factor). Homology-based molecular modeling of CD46 SCRs 3 and 4 revealed a cluster of positively charged residues between the interface of these SCR domains similar to the verified M protein binding sites on the plasma complement regulators factor H and C4b-binding protein. The presence of excess M6 protein did not inhibit the cofactor activity of CD46 and the presence of excess C3b did not inhibit the ability of CD46 to bind M6 protein by ELISA. In conclusion, 1) adherence of M6 GAS to keratinocytes is M protein dependent and 2) a major M protein binding site is located within SCRs 3 and 4, probably at the interface of these two domains, at a site distinct from the C3b-binding and cofactor site of CD46.

Amino Acid Sequence↗

PubMed2001

A functional interaction between CD46 and DLG4: a role for DLG4 in epithelial polarization.

Using a yeast two-hybrid screen, we identified a physical interaction between CD46 and DLG4. CD46 is a ubiquitous human cell-surface receptor for the complement components C3b and C4b and for measles virus and human herpesvirus 6. DLG4 is a scaffold protein important for neuronal signaling and is homologous to the Drosophila tumor suppressor DLG. We show that an interaction between CD46 and DLG4 is important for polarization in epithelial cells. Specifically, we show (i) biochemical evidence for an interaction between CD46 and DLG4, (ii) that this interaction is specific for the Cyt1 (but not Cyt2) domain of CD46, (iii) that both CD46 and an alternatively spliced isoform of DLG4 are polarized in normal human epithelial cells, and (iv) that the polarized expression of CD46 in epithelial cells requires the DLG4-binding domain and alters with expression of a truncated form of DLG4. This is the first identification of a direct and cytoplasmic domain-specific interaction between CD46 and an intracellular signaling molecule and provides a molecular mechanism for the polarization of CD46. These data also indicate that, in addition to the known role for DLG4 in neuronal cells, DLG4 may be important for polarization in epithelial cells.

Amino Acid Sequence↗