Vaccine delivery by penetratin: mechanism of antigen presentation by dendritic cells

Cell-penetrating peptides (CPP) or membrane-translocating peptides such as penetratin from Antennapedia homeodomain or TAT from human immunodeficiency virus are useful vectors for the delivery of protein antigens or their cytotoxic (Tc) or helper (Th) T cell epitopes to antigen-presenting cells. Mice immunized with CPP containing immunogens elicit antigen-specific Tc and/or Th responses and could be protected from tumor challenges. In the present paper, we investigate the mechanism of class I and class II antigen presentation of ovalbumin covalently linked to penetratin (AntpOVA) by bone marrow-derived dendritic cells with the use of biochemical inhibitors of various pathways of antigen processing and presentation. Results from our study suggested that uptake of AntpOVA is via a combination of energy-independent (membrane fusion) and energy-dependent pathways (endocytosis). Once internalized by either mechanism, multiple tap-dependent or independent antigen presentation pathways are accessed while not completely dependent on proteasomal processing but involving proteolytic trimming in the ER and Golgi compartments. Our study provides an understanding on the mechanism of antigen presentation mediated by CPP and leads to greater insights into future development of vaccine formulations

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

Alveolar Macrophage Polarisation in Lung Cancer

The role of alveolar macrophages in lung cancer is multifaceted and conflicting. Alveolar macrophage secretion of proinflammatory cytokines has been found to enhance antitumour functions, cytostasis (inhibition of tumour growth), and cytotoxicity (macrophage-mediated killing). In contrast, protumour functions of alveolar macrophages in lung cancer have also been indicated. Inhibition of antitumour function via secretion of the anti-inflammatory cytokine IL-10 as well as reduced secretion of proinflammatory cytokines and reduction of mannose receptor expression on alveolar macrophages may contribute to lung cancer progression and metastasis. Alveolar macrophages have also been found to contribute to angiogenesis and tumour growth via the secretion of IL-8 and VEGF. This paper reviews the evidence for a dual role of alveolar macrophages in lung cancer progression

Dendritic Cells Induce Immunity and Long-Lasting Protection against Blood-Stage Malaria despite an In Vitro Parasite-Induced Maturation Defect

Dendritic cells (DC) suffer a maturation defect following interaction with erythrocytes infected with malaria parasites and become unable to induce protective malaria liver-stage immunity. Here we show that, by contrast, maturation-arrested DC in vitro are capable of the successful induction of antigen-specific gamma interferon (IFN-γ) and interleukin 4 (IL-4) T-cell responses, antibody responses, and potent protection against lethal blood-stage malaria challenge in vivo. Similar results were found with DC pulsed with intact parasitized Plasmodium yoelii or Plasmodium chabaudi erythrocytes. Cross-strain protection was also induced. High levels of protection (80 to 100%) against lethal challenge were evident from 10 days after a single immunization and maintained up to 120 days. Interestingly, correlation studies versus blood-stage protection at different time points suggest that the immune effector mechanisms associated with protection could change over time. Antibody-independent, T-cell- and IL-12-associated protection was observed early after immunization, followed by antibody and IL-4-associated, IFN-γ-independent protection in long-term studies. These results indicate that DC, even when clearly susceptible to parasite-induced maturation defect effects in vitro, can be central to the induction of protection against blood-stage malaria in vivo

Characterization of Blood Monocyte Phenotype in Patients with Endometrial Cancer

Background: Endometrial tumors induce various tumor escape mechanisms that result in immunosuppression in patients and, ultimately, tumor progression. Blood monocytes are able to exhibit potent cytotoxic action against tumor cells where novel immunotherapeutics targeting antigen-presenting cells including dendritic cells, and blood monocytes are being used as a means of delivering immunogens to stimulate an antitumor and, ultimately, therapeutic response. This study shows that peripheral blood monocytes from patients with endometrial cancer show functional deficiencies, and these deficiencies can be characterized by phenotypic changes as well as altered cytokine secretion

Whole protein and defined CD8 + and CD4 + peptides linked to penetratin targets both MHC class i and II antigen presentation pathways

Cytoplasmic delivery and cross-presentation of proteins and peptides is necessary for processing and presentation of antigens for the generation of cytotoxic T cells. We previously described the use of the 16 amino acid peptide penetratin from the Drosophila Antennapedia homeodomain (penetratin, Antp) to transport cytotoxic T lymphocyte epitopes derived from ovalbumin (OVA) or the Mucin-1 tumor-associated antigen into cells. We have now shown that penetratin covalently conjugated to OVA protein and linked in tandem to CD4+ and/or CD8+ T-cell epitopes from OVA-stimulated T cells in vitro (B3Z T-cell hybridoma and OT-I and OT-II T cells). The induction of these responses was directly mediated by the penetratin peptide as linking a nonspecific 16-mer peptide to OVA or mixing did not induce CD8+ or CD4+ T-cell responses in vitro. Furthermore, interferon (IFN)-γ-secreting CD4+ and CD8+ T cells were induced which suppressed B16.OVA tumor growth in C57BL/6 mice. Tumor protection was mediated by a CD8+ T-cell-dependent mechanism and did not require CD4+ help to protect mice 7 days after a boost immunization. Alternatively, 40 days after a boost immunization, the presence of CD4+ help enhanced antigen-specific IFN-γ-secreting CD8+ T cells and tumor protection in mice challenged with B16.OVA. Long-term CD8 responses were equally enhanced by antigen-specific and universal CD4 help. In addition, immunization with AntpOVA significantly delayed growth of B16.OVA tumors in mice in a tumor therapy model