Autophagy, citrullination and cancer (2016)

Autophagy, citrullination and cancer (2016)

Lindy G. Durrant, Rachael L. Metheringham and Victoria A. Brentville

ABSTRACT: A cell needs to maintain a balance between biosynthesis and degradation of cellular components to maintain homeostasis. There are 2 pathways, the proteasome, which degrades short-lived proteins, and the autophagy/lysosomal pathway, which degrades long-lived proteins and organelles. Both of these pathways are also involved in antigen presentation or the effective delivery of peptides to MHC molecules for presentation to T cells. Autophagy (macroautophagy) is a key player in providing substantial sources of citrullinated peptides for loading onto MHC-II molecules to stimulate CD4+ T cell responses. Stressful conditions in the tumor microenvironment induce autophagy in cancer cells as a mechanism to promote their survival. We therefore investigated if citrullinated peptides could stimulate CD4+ T cell responses that would recognize these modifications produced during autophagy within tumor cells. Focusing on the intermediate filament protein VIM (vimentin), we generated citrullinated VIM peptides for immunization experiments in mice. Immunization with these peptides induced CD4+ T cells in response to autophagic tumor targets. Remarkably, a single immunization with modified peptide, up to 14 days after tumor implant, resulted in long-term survival in 60% to 90% of animals with no associated toxicity. These results show how CD4+ cells can mediate potent antitumor responses against modified self-epitopes presented on tumor cells, and they illustrate for the first time how the citrullinated peptides produced during autophagy may offer especially attractive vaccine targets for cancer therapy.

Citrullinated Vimentin presented on MHC-II in Tumor Cells is a target for CD4þ T-cell-mediated antitumor immunity (2016)

Citrullinated Vimentin presented on MHC-II in Tumor Cells is a target for CD4þ T-cell-mediated antitumor immunity (2016)

Victoria A. Brentville, Rachael L. Metheringham, Barbara Gunn, Peter Symonds, Ian Daniels, Mohamed Gijon, Katherine Cook, Wei Xue and Lindy G. Durrant 

ABSTRACT: Stressful conditions in the harsh tumor microenvironment induce autophagy in cancer cells as a mechanism to promote their survival.However, autophagy also causes post-translational modification of proteins that are recognized by the immune system. In particular, modified self-antigens can trigger CD4+ T-cell responses that might be exploited to boost antitumor immune defenses. In this study, we investigated the ability of CD4 cells to target tumor-specific self-antigens modified by citrullination, which converts arginine residues in proteins to citrulline. Focusing on the intermediate filament protein vimentin, which is frequently citrullinated in cells during epithelial-tomesenchymal transition of metastasizing epithelial tumors, we generated citrullinated vimentin peptides for immunization experiments in mice. Immunization with these peptides induced IFNγ- and granzyme B-secreting CD4 T cells in response to autophagic tumor targets. Remarkably, a single immunization with modified peptide, up to 14 days after tumor implant, resulted in long-term survival in 60% to 90% of animals with no associated toxicity. This antitumor response was dependent on CD4 cells and not CD8+ T cells. These results show how CD4 cells can mediate potent antitumor responses against modified self-epitopes presented on tumor cells, and they illustrate fort he first time how the citrullinated peptides may offer especially attractive vaccine targets for cancer therapy. Cancer Res; 76(3); 548–60. 2015 AACR.

Progress in Vaccination against Cancer 2015

PIVAC 2015 SCIB2 Poster

Wei Xue, Rachael Metheringham, Victoria Brentville, Katherine Cook, Peter Symonds, Ian Daniel and Lindy Durrant

PIVAC 2015 Moditope poster 2

V. Brentville, W. Xue, P. Symonds, K. Cook, B. Gunn, R. Metheringham and L.G. Durrant

PIVAC 2015 SCIB1 resected disease

L.G. Durrant, C. Ottensmeier, C. Mulatero, P. Lorigan, R. Plummer, R. Metheringham, V. Brentville, L. Machado, I. Daniels, D. Hannaman and P.M. Patel

PIVAC 2015 SCIB1 plus checkpoint inhibition

Wei Xue, Victoria Brentville, Rachael Metheringham, Katherine Cook, Peter, Symonds, Ian Daniels and Lindy Durrant

High avidity cytotoxic T lymphocytes can be selected into the memory pool but they are exquisitely sensitive to functional impairment (2012)

High avidity cytotoxic T lymphocytes can be selected into the memory pool but they are exquisitely sensitive to functional impairment (2012) 

Victoria A. Brentville, Rachael L. Metheringham, Barbara Gunn and Lindy G. Durrant

ABSTRACT: High avidity cytotoxic T lymphocytes (CTL) are important in viral clearance and anti-tumor immunity, however, mechanisms for their optimal generation and maintenance in vivo remain unclear. Immunizing mice with an antibody-DNA vaccine encoding a single CTL epitope, induces a 100 fold higher avidity response than peptide vaccination with the identical epitope. The high avidity response is retained into memory and can be efficiently reactivated with an antibody-DNA boost. In contrast, reactivation of high avidity CTL with peptide, stimulated responses with a significant drop in avidity, suggesting loss or conversion of the high avidity CTL to lower avidity. Similarly, high avidity T cells maintained ex vivo were exquisitely sensitive to signaling with low doses of peptide (1 ng/ml) giving optimal TCR stimulation and resulting in retained avidity, proliferation and ability to kill specific targets. In contrast, high avidity T cells maintained ex vivo with supraoptimal TCR stimulation (10 μg/ml peptide) resulted in reduced avidity and failure to kill tumor cells. They also failed to proliferate, showed a significant increase in apoptosis and expressed high levels of the exhaustion marker programmed death-1 (PD-1) and low levels of the lymphocyte-activation gene 3 (LAG-3). This suggests high avidity T cells are recruited to the memory pool but can be lost by supraoptimal stimulation in vitro and in vivo. This is characterized by loss of function and an increase in cell death. The remaining CTL, exhibit low functional avidity that is reflected in reduced anti-tumor activity. This could contribute to failure of the immune system to control the growth of tumors and has implications for vaccination strategies and adoptive transfer of T cells.

DNA vaccination with T-cell epitopes encoded within Ab molecules induces high-avidity anti-tumor CD8 T cells (2009)

DNA vaccination with T-cell epitopes encoded within Ab molecules induces high-avidity anti-tumor CD8 T cells (2009)

Victoria A. Pudney, Rachael L. Metheringham, Barbara Gunn, Ian Spendlove, Judith M. Ramage and Lindy G. Durrant

ABSTRACT: Stimulation of high-avidity CTL responses is essential for effective anti-tumor and antiviral vaccines. In this study we have demonstrated that a DNA vaccine incorporating CTL epitopes within an Ab molecule results in high-avidity T-cell responses to both foreign and self epitopes. The avidity and frequency was superior to peptide, peptide-pulsed DC vaccines or a DNA vaccine incorporating the epitope within the native Ag. The DNA Ab vaccine was superior to an identical proteinvaccine that can only cross-present, indicating a role for direct presentation by the DNA vaccine. However, the avidity of CTL responses was significantly reduced in Fc receptor γ knockout mice or if the Fc region was removed suggesting that cross presentation of Ag via Fc receptor was also important in the induction of high-avidity CTL. These results suggest that generation of high-avidity CTL responses by the DNA vaccine is related to its ability to both directly present and crosspresent the epitope. High-avidity responses were capable of efficient anti-tumor activity in vitro and in vivo. This study demonstrates a vaccine strategy to generate high-avidity CTL responses that can be used in anti-tumor and anti-viral vaccine settings