Preclinical efficacy of dendritic cells loaded with newly identified HPV11 E6-derived CD8⁺ T cell epitopes

Although the low-risk human papillomaviruses (HPVs), including HPV11, are mainly associated with low-grade lesions, they are also implicated in otolaryngologic malignancies and lung carcinomas. Nonetheless, T cell responses to the low-risk HPVs remain poorly understood. This study investigated HPV11 E6/7-specific T cell responses in C57BL/6 mice challenged with TC-1 tumor cells expressing HPV11 E6/7 proteins (TC-1.HPV11 E6/7). We identified two major CD8⁺ T cell epitopes, HPV11 E6_41-55 (AEIYAYAYKNLKVVW, p11) and E6_85-99 (YAPTVEEETNEDILK, p22). We next demonstrated that IFNα-matured bone marrow-derived dendritic cells (BMDCs) loaded with peptides p11 or p22 induced p11- and p22-specific CD8⁺ T cell responses, respectively. Furthermore, the administration of p11- or p22-loaded BMDCs matured with IFNα or BMDCs generated in the presence of p38 inhibitor/IL-15 and matured with TNFα, IL-1β, and prostaglandin E2, suppressed TC-1.HPV11.E6/7 tumor progression with increased infiltrations of p11- and p22-specific IFNγ⁺, TNFα⁺, and granzyme B⁺ CD8⁺ T cells in the tumors. In addition, BMDCs loaded with both peptide epitopes, p11 and p22, were more effective than BMDCs loaded with single epitopes in the suppression of TC-1.HPV11 E6/7 tumor progression. Data from this study will help with the rational design of therapeutic strategies for the diseases associated with HPV11 infection.