Graham R Leggatt

Publications (93) View all

• Article: Inhibition of cervical cancer cell growth in vitro and in vivo with lentiviral-vector delivered short hairpin RNA targeting human papillomavirus E6 and E7 oncogenes.

  W Gu, L Putral, K Hengst, K Minto, N A Saunders, G Leggatt, N A J McMillan
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  ABSTRACT: In this study, we investigated the suppressive effect of a short hairpin RNA delivered by a lentiviral vector (LV-shRNA) against human papillomavirus (HPV) type 18 E6 on the expression of the oncogenes E6 and E7 in cervical cancer HeLa cells both in vitro and in vivo. The LV-shRNA effectively delivered the shRNA to HeLa cells and lead to a dose-dependent reduction of E7 protein and the stabilization of E6 target proteins, p53 and p21. Low-dose infection of HeLa cells with LV-shRNA caused reduced cell growth and the induction of senescence, whereas a high-dose infection resulted in specific cell death via apoptosis. Transplant of HeLa cells infected with a low dose of LV-shRNA into Rag-/- mice significantly reduced the tumor weight, whereas transplant of cells infected with a high dose resulted in a complete loss of tumor growth. Systemic delivery of LV-shRNA into mice with established HeLa cell lung metastases led to a significant reduction in the number of tumor nodules. Our data collectively suggest that lentiviral delivery is an effective way to achieve stable suppression of E6/E7 oncogene expression and induce inhibition of tumor growth both in vitro and in vivo. These results encourage further investigation of this form of RNA interference as a promising treatment for cervical cancer.
  Cancer Gene Therapy 12/2006; 13(11):1023-32. · 2.80 Impact Factor
• Article: Route of administration of chimeric BPV1 VLP determines the character of the induced immune responses.

  Xiao Song Liu, Wen Jun Liu, Kong Nan Zhao, Yue Hua Liu, Graham Leggatt, Ian H Frazer
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  ABSTRACT: To examine the mucosal immune response to papillomavirus virus-like particles (PV-VLP), mice were immunized with VLP intrarectally (i.r.), intravaginally (i.va.) or intramuscularly (i.m.) without adjuvant. PV-VLP were assembled with chimeric BPV-1 L1 proteins incorporating sequence from HIV-1 gp120, either the V3 loop or a shorter peptide incorporating a known CTL epitope (HIVP18I10). Antibody specific for BPV-1 VLP and P18 peptide was detected in serum following i.m., but not i.r. or i.va. immunization. Denatured VLP induced a much reduced immune response when compared with native VLP. Immune responses following mucosal administration of VLP were generally weaker than following systemic administration. VLP specific IgA was higher in intestine washes following i.r. than i.va. immunization, and higher in vaginal washes following i.m. than i.r. or i.va. immunization. No differences in specific antibody responses were seen between animals immunized with BPV-1 P18 VLP or with BPV-1 V3 VLP. Cytotoxic T lymphocyte precursors specific for the P18 CTL epitope were recovered from the spleen following i.m., i.va. or i.r. immunization with P18 VLP, and were similarly detected in Peyer's patches following i.m. or i.r. immunization. Thus, mucosal or systemic immunization with PV VLP induces mucosal CTL responses and this may be important for vaccines for mucosal infection with human papillomaviruses and for other viruses.
  Immunology and Cell Biology 03/2002; 80(1):21-9. · 3.66 Impact Factor
• Article: A Combination of Local Inflammation and Central Memory T Cells Potentiates Immunotherapy in the Skin.

  Salvatore Fiorenza, Tony J Kenna, Iain Comerford, Shaun McColl, Raymond J Steptoe, Graham R Leggatt, Ian H Frazer
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  ABSTRACT: Adoptive T cell therapy uses the specificity of the adaptive immune system to target cancer and virally infected cells. Yet the mechanism and means by which to enhance T cell function are incompletely described, especially in the skin. In this study, we use a murine model of immunotherapy to optimize cell-mediated immunity in the skin. We show that in vitro-derived central but not effector memory-like T cells bring about rapid regression of skin-expressing cognate Ag as a transgene in keratinocytes. Local inflammation induced by the TLR7 receptor agonist imiquimod subtly yet reproducibly decreases time to skin graft rejection elicited by central but not effector memory T cells in an immunodeficient mouse model. Local CCL4, a chemokine liberated by TLR7 agonism, similarly enhances central memory T cell function. In this model, IL-2 facilitates the development in vivo of effector function from central memory but not effector memory T cells. In a model of T cell tolerogenesis, we further show that adoptively transferred central but not effector memory T cells can give rise to successful cutaneous immunity, which is dependent on a local inflammatory cue in the target tissue at the time of adoptive T cell transfer. Thus, adoptive T cell therapy efficacy can be enhanced if CD8(+) T cells with a central memory T cell phenotype are transferred, and IL-2 is present with contemporaneous local inflammation.
  The Journal of Immunology 11/2012; · 5.79 Impact Factor
• Article: TLR7 stimulation augments T effector-mediated rejection of skin expressing neo-self antigen in keratinocytes.

  Jie Zhong, Usriansyah Hadis, Rachel De Kluyver, Graham R Leggatt, Germain J P Fernando, Ian H Frazer
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  ABSTRACT: Immunotherapy generally fails to induce tumour regression in spontaneously arising tumours. Failure is attributed to both tumour-related factors and an ineffective immune response. As a model of tumour immunotherapy, without the confounding effects of potential tumour-determined mechanisms of immune evasion, we studied the requirements for rejection of skin grafts expressing a neo-self antigen in somatic cells and not in antigen-presenting cells. When antigen expression was restricted to somatic cells, both CD4(+) and CD8(+) effector cells were required for graft rejection. Although freshly placed grafts were spontaneously rejected, healed grafts established under the cover of T cell depletion were not rejected even after T cell numbers recovered to a level where freshly placed grafts on the same animal were rejected, suggesting that healed skin grafts expressing a neo-self antigen only in somatic cells could not be rejected by primed recipients with functional effector T cells. Local TLR7 ligation induced inflammatory responses and rejection of healed grafts exposed to the TLR agonist but did not induce rejection of untreated healed grafts on the same animal. Thus, local pro-inflammatory signalling via TLR7 can promote effector T cell function against skin cells displaying their nominal antigen.
  European Journal of Immunology 02/2008; 38(1):73-81. · 5.10 Impact Factor
• Article: HPV vaccines: the beginning of the end for cervical cancer.

  Graham R Leggatt, Ian H Frazer
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  ABSTRACT: Vaccines prophylactic against infection with human papillomavirus (HPV) are based on alum adjuvanted virus-like particles. Two such vaccines have recently been shown to prevent persistent HPV infection and associated cervical cancer precursor lesions. The genotype-specific neutralising antibody directed at conformational epitopes of the L1 major capsid protein is likely to mediate protection. Vaccines therapeutic for persisting HPV infection can eliminate transplantable tumors in animal models, but are of limited efficacy in mice grafted with skin that expresses HPV antigens or in humans. This paradox has been partially resolved by data clarifying the immunoregulatory role of skin cytokines (e.g. transforming growth factor-beta and interleukin-10) and the consequences of antigen presentation by subsets of skin-associated antigen-presenting cells.
  Current Opinion in Immunology 05/2007; 19(2):232-8. · 9.52 Impact Factor