Identification of promiscuous HPV16-derived T helper cell epitopes for therapeutic HPV vaccine design

Abstract

Cervical carcinoma and several other human papillomavirus (HPV)-induced malignancies are a global public health problem, thus novel treatment modalities are urgently needed. Immunotherapy is an attractive option for treatment of HPV infection and HPV-mediated premalignant and malignant lesions. However, previous approaches-focusing on the induction of cytotoxic CD81 T cells (CTLs)-have as yet not yielded clinical successes. Since CD41 T cells have been shown to be crucial for the induction and maintenance of CTL responses, and more recently to be also important for direct anti-tumor immunity, human leukocyte antigen (HLA) class II-restricted epitopes are intensively investigated to improve the efficacy of peptide-based HPV immunotherapy. We here present an approach to identify promiscuous HPV16-derived CD41 T helper epitopes, which are capable of inducing T cell immunity in a large proportion of the population. To this end, we combined HLA class II epitope prediction servers with in vitro immunological evaluation to identify HPV16 E2-, E5-, E6-, and E7-derived CD41 T cell epitopes. Candidate selected HPV16-derived epitopes were found to be restricted by up to nine HLA-DR molecules. Furthermore, they were found to induce frequent and robust HPV16 peptide-specific Th1 responses in healthy donors, as monitored by interferon (IFN)-c ELISPOT and cytokine secretion assays. Moreover, these selected peptides also induced specific IFN-c T cell responses in blood from HPV161 CIN2/3 and cervical carcinoma patients. We thus conclude that the identified T helper epitopes are valuable candidates for the development of a comprehensive therapeutic HPV vaccine.High-risk types of human papillomavirus (HPV) are associated with several malignant diseases, including cervical carcinoma (CxCa), other anogenital tumors and oropharyngeal carcinomas. 1-3 Natural history studies indicate that nearly every sexually active individual will acquire at least one highrisk HPV infection during their lifetime. 4,5 Fortunately, the majority of HPV infections are eradicated by the host immune system within 1-2 years of acquisition, 6,7 and only <1% of infected people develop HPV-mediated cancers. 8,9 Why some individuals clear the viral infection, while others do not, is still incompletely understood. Accumulating data suggest that both cytotoxic CD81 T cell (CTL) and CD41 T helper (Th) cell responses play a pivotal role in the control and clearance of HPV infection. [10][11][12][13] To date, however, the majority of therapeutic HPV vaccines have been designed to elicit tumor-specific CTL responses. 14-16 Unfortunately, only disappointing clinical outcomes have been observed, with the exception of one study with synthetic long peptides in vulvar intraepithelial neoplasia. 17 Exclusive targeting of HLA (human leukocyte antigen) class I-restricted CTL HPV epitopes, without involving specific T-cell help, can lead to suboptimal and short-lasting CD81 T cell responses. The lessons learned from these clinical studies lead to a rethinking of therapeutic ...

Bladder cancer-associated cancer-testis antigen-derived long peptides encompassing both CTL and promiscuous HLA class II-restricted Th cell epitopes induced CD4+ T cells expressing converged T-cell receptor genes in vitro

“…Previous phase I/II clinical trials have shown that vaccination with a DEPDC1-SP and an MPHOSPH1-SP alone did not induce dramatic antitumor effects. 27,29,30 We have demonstrated herein that DEPDC1-and MPHOSPH1-LPs were presented by HLA-DR4, HLA-DR9, HLA-DR15, HLA-DR53, HLA-DP2, and HLA-DP5, suggesting that vaccination with a combination of DEPDC1-and MPHOSPH1-LPs could cover the majority of the Japanese population (Table S4). Although both HD1 and HD4 are DR4-positive, Th cells generated from HD4 was restricted by HLA-DR4 in respect to IFN-g production upon stimulation with DEPDC1-LP1, but Th cells generated from HD1 was restricted by DR53, resulting in a difference in HLA restriction of Th cells specific to the same DEPDC1-LP1.…”

“…Nonamer SPs (DEPDC1-A2 302-311 , DEPDC1-A24 294-302 , MPHOSPH1-A24 278-286 , and MPHOSPH1-A2 282-291 ) that are recognized by HLA-A2-or HLA-A24-restricted CTLs are indicated with underlined bold letters. that these LPs were promiscuous Th-cell epitopes presented by frequently observed HLA class II molecules in the Japanese population (Table S4) as expeted, 27,28 and combination of these peptides would induce DEPDC1-or MPHOSPH1-specific Th-cell responses in PBMCs of many Japanese donors.…”

The Interaction Between Human Papillomaviruses and the Stromal Microenvironment

“…Lack of Th1 response is related to long-term viral persistence 332,333,335 . Stimulation of an effective cell- mediated immune response by therapeutic vaccination remains a major goal in HPV research 336 , but despite the fact that T cell responses against HPV early proteins are possible 337 , HPVs have developed numerous methods to circumvent effective T cell immunity.…”

Interest of Tumor-Specific CD4 T Helper 1 Cells for Therapeutic Anticancer Vaccine

“…Furthermore, there exists clear evidence for epitope spreading, following immunization of cancer patients with tumor-reactive helper peptides [ 77 , 78 , 79 ]. Collectively, these results highlighted the necessity of tumor-specific CD4 T cell stimulation for vaccine success [ 49 , 80 , 81 , 82 ].…”