Identification of key amino acid residues that determine the ability of high risk HPV16-E7 to dysregulate major histocompatibility complex class I expression

Unraveling Immunological Dynamics: HPV Infection in Women-Insights from Pregnancy

During pregnancy, hormonal and immune adaptations are vital for supporting the genetically distinct fetus during elevated infection risks. The global prevalence of HPV necessitates its consideration during pregnancy. Despite a seemingly mild immune response, historical gestational viral infections underscore its significance. Acknowledging the established HPV infection risks during pregnancy, our review explores the unfolding immunological changes in pregnant women with HPV. Our analysis aims to uncover strategies for safely modulating the immune system, mitigating adverse pregnancy consequences, and enhancing maternal and child health. This comprehensive narrative review delves into the existing knowledge and studies on this topic.

Tumor Immune Microenvironment in Gynecologic Cancers

Gynecologic cancers have varying response rates to immunotherapy due to the heterogeneity of each cancer's molecular biology and features of the tumor immune microenvironment (TIME). This article reviews key features of the TIME and its role in the pathophysiology and treatment of ovarian, endometrial, cervical, vulvar, and vaginal cancer. Knowledge of the role of the TIME in gynecologic cancers has been rapidly developing with a large body of preclinical studies demonstrating an intricate yet dichotomous role that the immune system plays in either supporting the growth of cancer or opposing it and facilitating effective treatment. Many targets and therapeutics have been identified including cytokines, antibodies, small molecules, vaccines, adoptive cell therapy, and bacterial-based therapies but most efforts in gynecologic cancers to utilize them have not been effective. However, with the development of immune checkpoint inhibitors, we have started to see the rapid and successful employment of therapeutics in cervical and endometrial cancer. There remain many challenges in utilizing the TIME, particularly in ovarian cancer, and further studies are needed to identify and validate efficacious therapeutics.

Reduced MHC Class I and II Expression in HPV-Negative vs. HPV-Positive Cervical Cancers

Cervical cancer (CC) is the second most common cancer in women worldwide and the fourth leading cause of cancer-associated death in women. Although human papillomavirus (HPV) infection is associated with nearly all CC, it has recently become clear that HPV-negative (HPV-) CC represents a distinct disease phenotype with increased mortality. HPV-positive (HPV+) and HPV- CC demonstrate different molecular pathology, prognosis, and response to treatment. Furthermore, CC caused by HPV α9 types (HPV16-like) often have better outcomes than those caused by HPV α7 types (HPV18-like). This study systematically and comprehensively compared the expression of genes involved in major histocompatibility complex (MHC) class I and II presentation within CC caused by HPV α9 types, HPV α7 types, and HPV- CC. We observed increased expression of MHC class I and II classical and non-classical genes in HPV+ CC and overall higher expression of genes involved in their antigen loading and presentation apparatus as well as transcriptional regulation. Increased expression of MHC I-related genes differs from previous studies using cell culture models. These findings identify crucial differences between antigen presentation within the tumor immune microenvironments of HPV+ and HPV- CC, as well as modest differences between HPV α9 and α7 CC. These differences may contribute to the altered patient outcomes and responses to immunotherapy observed between these distinct cancers.

The association of cervicovaginal Langerhans cells with clearance of human papillomavirus

Human papillomavirus (HPV) clearance is important in eliminating cervical cancer which contributes to high morbidity and mortality in women. Nevertheless, it remains largely unknown about key players in clearing pre-existing HPV infections. HPV antigens can be detected by the most important cervical antigen-presenting cells (Langerhans cells, LCs), of which the activities can be affected by cervicovaginal microbiota. In this review, we first introduce persistent HPV infections and then describe HPV-suppressed LCs activities, including but not limited to antigen uptake and presentation. Given specific transcriptional profiling of LCs in cervical epithelium, we also discuss the impact of cervicovaginal microbiota on LCs activation as well as the promise of exploring key microbial players in activating LCs and HPV-specific cellular immunity.

A novel lineage-tracing mouse model for studying early MmuPV1 infections

Human papillomaviruses are DNA viruses that ubiquitously infect humans and have been associated with hyperproliferative lesions. The recently discovered mouse specific papillomavirus (MmuPV1) provides the opportunity to study papillomavirus infections in vivo in the context of a common laboratory mouse model (Mus musculus). To date, a major challenge in the field has been the lack of tools to identify, observe, and characterize individually the papillomavirus hosting cells and also trace the progeny of these cells over time. Here, we present the successful generation of an in vivo lineage-tracing model of MmuPV1-harboring cells and their progeny by means of genetic reporter activation. Following the validation of the system both in vitro and in vivo, we used it to provide a proof-of-concept of its utility. Using flow-cytometry analysis, we observed increased proliferation dynamics and decreased MHC-I cell surface expression in MmuPV1-treated tissues which could have implications in tissue regenerative capacity and ability to clear the virus. This model is a novel tool to study the biology of the MmuPV1 host-pathogen interactions.

Human Papillomavirus 16 E6 Suppresses Transporter Associated with Antigen-Processing Complex in Human Tongue Keratinocyte Cells by Activating Lymphotoxin Pathway

Simple Summary

There is still limited knowledge of the critical pathogenic processes by which HPV16 induces oral carcinogenesis. Therefore, we aimed to illuminate the oncogenic role of HPV16 in the context of oral squamous cell carcinomas (OSCCs). Using human tongue keratinocyte cells, we demonstrated that HPV16 E6 promotes LTα₁β₂ and LTβR expression, thus promoting the lymphotoxin signaling pathway and leading to suppression of the transporter associated with the antigen-processing complex (TAPs; TAP1 and TAP2). Additionally, in vitro, we also demonstrated regulation of the antigenic peptide-loaded machinery in HPV-infected OSCC tissues through analysis of the transcriptomic profiles of the head and neck squamous cell carcinoma (HNSCC) cohort from the TCGA database, which was validated using fresh biopsied specimens. Thus, our study enhances the proposed functional role of HPV16 E6-associated immune-evasive properties in oral epithelial cells, revealing a possible mechanism underlying the development of HPV-mediated OSCCs.

Abstract

Infection by high-risk human papillomaviruses (hrHPVs), including HPV type 16 (HPV16), is a major risk factor for oral squamous cell carcinomas (OSCCs). However, the pathogenic mechanism by which hrHPVs promote oral carcinogenesis remains to be elucidated. Here, we demonstrated that the suppression of a transporter associated with the antigen-processing complex (TAPs; TAP1 and TAP2), which is a key molecule in the transportation of viral antigenic peptides into MHC class-I cells, is affected by the E6 protein of HPV16. Mechanistically, HPV-mediated immune evasion is principally mediated via the signal-transduction network of a lymphotoxin (LT) pathway, in particular LTα₁β₂ and LTβR. Our analysis of transcriptomic data from an HNSCC cohort from the Cancer Genome Atlas (TCGA) indicated that expression of TAP genes, particularly TAP2, was downregulated in HPV-infected cases. We further demonstrated that LTα₁β₂ and LTβR were upregulated, which was negatively correlated with TAP1 and TAP2 expression in HPV-positive clinical OSCC samples. Taken together, our findings imply that HPV16 E6 regulates the machinery of the antigenic peptide-loading system and helps to clarify the role of oncogenic viruses in the context of oral carcinoma.

HPV16 E6 gene polymorphisms and the functions of the mutation site in cervical cancer among Uygur ethnic and Han nationality women in Xinjiang, China

BACKGROUND

To investigate the genotype distribution of human papillomavirus (HPV) in infected Uygur and Han women in Xinjiang, China; analyze the HPV16 E6 gene polymorphism site and relationship with the development of cervical cancer.

METHODS

The HPV16 E6 sequence was analyzed using the European standard prototype to perform an evolutionary tree. HPV16 E6-T295/T350, G295/G350, and T295/G350 GV230 vectors were stably transfected into cervical cancer C33A cells to analyze the cell proliferation, migration and invasion, apoptosis by CCK8 and clonogenic assays, transwell and cell scratch assays, FACS experiments.

RESULTS

The total HPV infection rate was 26.390% (760/2879), whereas the Uygur 22.87% (196/857) and the Han was 27.89% (564/2022) (P < 0.05). Among 110 mutations, 65 cases of E6 genes were mutated at nucleotide 350 (T350G) with the leucine changing to valine (L83V). Moreover, there were 7 cases of E6 gene mutated at nucleotide 295 (T295G) with aspartic changing to glutamic (D64E). When E6 vector(s) of mutations sites were transfected into C33A cells, they were found to promote cellular proliferation, migration, invasion, and inhibit apoptosis. T295/G350-E6 was significantly stronger than G295/G350 and T295/T350, G295/G350 was significantly stronger than T295/T350 (P < 0.05). The T295/G350 had the strongest effect on C33A cells and G295/G350 was significantly stronger than T295/T350 (P < 0.05).

CONCLUSIONS

The positive HPV infection rates differed between the Uygur and Han in Xinjiang, China, and the genotype distribution of infection was different. After transfecting C33A cells with different eukaryotic expression vectors, the T295/G350 mutation site promoted the proliferation, migration, and invasion of C33A cells to a greater extent than G295/G350; however, G295/G350 had a stronger effect than T295/T350.

Role of interleukin-17 in human papillomavirus infection and associated malignancies

Human papillomavirus infection is among the leading viral infections in the world, causing severe mortality and morbidity. The virus mainly targets the female genital tract-cervix, vulva, anus but it is also reported to infect the lungs and oropharyngeal region of the body. The host immune response plays a vital role in the persistence of viral infection. Interleukin 17 (IL-17) is mainly secreted by Th17 cells and mediates the immune response that enhances the disease severity in HPV infection. IL-17 is reported to promote lesions and tumour progression by creating a hyperinflammatory condition leading to cancer. The current minireview summarizes the pathogenic role of IL-17 in HPV infection and HPV-induced malignancies. Further study on IL-17 associated pathology of HPV infection would be useful in developing therapeutic measures.

Cervicovaginal Microbiome Factors in Clearance of Human Papillomavirus Infection

Persistent high-risk human papillomavirus (hrHPV) infection is the highest risk to cervical cancer which is the fourth most common cancer in women worldwide. A growing body of literatures demonstrate the role of cervicovaginal microbiome (CVM) in hrHPV susceptibility and clearance, suggesting the promise of CVM-targeted interventions in protecting against or eliminating HPV infection. Nevertheless, the CVM-HPV-host interactions are largely unknown. In this review, we summarize imbalanced CVM in HPV-positive women, with or without cervical diseases, and the progress of exploring CVM resources in HPV clearance. In addition, microbe- and host-microbe interactions in HPV infection and elimination are reviewed to understand the role of CVM in remission of HPV infection. Lastly, the feasibility of CVM-modulated and -derived products in promoting HPV clearance is discussed. Information in this article will provide valuable reference for researchers interested in cervical cancer prevention and therapy.

The Role of the Cervicovaginal and Gut Microbiome in Cervical Intraepithelial Neoplasia and Cervical Cancer

The microbiome, which refers to the microbiota within a host and their collective genomes, has recently been demonstrated to play a critical role in cancer progression, metastasis, and therapeutic response. The microbiome is known to affect host immunity, but its influence on human papilloma virus (HPV) gynecologic malignancies remains limited and poorly understood. To date, studies have largely focused on the cervicovaginal microbiome; however, there is growing evidence that the gut microbiome may interact and substantially affect therapeutic response in gynecologic cancers. Importantly, new developments in microbiome sequencing and advanced bioinformatics technologies have enabled rapid advances in our understanding of the gut and local tumor microbiota. In this review, we examine the evidence supporting the role of the microbiome in HPV-associated cervical intraepithelial neoplasia (CIN) and cervical cancer, explore characteristics that influence and shape the host microbiota that impact HPV-driven carcinogenesis, and highlight potential approaches and considerations for future and ongoing research of the microbiome's effect on HPV-associated cancer.

Identification of critical amino acid residues in the regulatory N-terminal domain of PMEL

The pigment cell-specific protein PMEL forms a functional amyloid matrix in melanosomes onto which the pigment melanin is deposited. The amyloid core consists of a short proteolytic fragment, which we have termed the core-amyloid fragment (CAF) and perhaps additional parts of the protein, such as the PKD domain. A highly O-glycosylated repeat (RPT) domain also derived from PMEL proteolysis associates with the amyloid and is necessary to establish the sheet-like morphology of the assemblies. Excluded from the aggregate is the regulatory N-terminus, which nevertheless must be linked in cis to the CAF in order to drive amyloid formation. The domain is then likely cleaved away immediately before, during, or immediately after the incorporation of a new CAF subunit into the nascent amyloid. We had previously identified a 21 amino acid long region, which mediates the regulatory activity of the N-terminus towards the CAF. However, many mutations in the respective segment caused misfolding and/or blocked PMEL export from the endoplasmic reticulum, leaving their phenotype hard to interpret. Here, we employ a saturating mutagenesis approach targeting the motif at single amino acid resolution. Our results confirm the critical nature of the PMEL N-terminal region and identify several residues essential for PMEL amyloidogenesis.

Evaluation of HPV16 E7 expression in head and neck carcinoma cell lines and clinical specimens

Human papillomavirus (HPV) 16 infection in the oropharynx is one of the major risk factors for oropharyngeal carcinoma. Although the HPV E6 and E7 proteins are known to have a role in head and neck carcinogenesis, whether their expression is maintained once the tumour has developed still remains unclear. We evaluated the expression of these proteins in HPV16-positive cancer cell lines and clinical oropharyngeal specimens. Two out of the four commercially available antibodies directed against the E7 protein could detect the E7 protein overexpressed in the 293FT cells, human embryonic kidney cells, although none of the four commercially available anti-E6 antibodies could detect the overexpressed E6 protein. Whereas HPV16-positive head and neck or cervical carcinoma cell lines expressed the E7 mRNA, the antibodies with an ability to detect the E7 protein could not detect it in western blotting in these HPV16-positive cell lines. In clinical specimens, E7 protein was partially detected in p16-positive area in p16-positive and HPV16 DNA-positive samples, but not in p16-negative and HPV DNA-negative or p16-positive and HPV DNA-negative samples. Consistent with these findings, the E7 protein was poorly translated from the endogenous structure of the E7 mRNA, although significant E7 mRNA expression was detected in these samples. Our findings indicate that E7 protein is partially expressed in p16-positive area in p16-positive and HPV16 DNA-positive clinical specimens.

Protecting Tumors by Preventing Human Papilloma Virus Antigen Presentation: Insights from Emerging Bioinformatics Algorithms

Recent developments in bioinformatics technologies have led to advances in our understanding of how oncogenic viruses such as the human papilloma virus drive cancer progression and evade the host immune system. Here, we focus our review on understanding how these emerging bioinformatics technologies influence our understanding of how human papilloma virus (HPV) drives immune escape in cancers of the head and neck, and how these new informatics approaches may be generally applicable to other virally driven cancers. Indeed, these tools enable researchers to put existing data from genome wide association studies, in which high risk alleles have been identified, in the context of our current understanding of cellular processes regulating neoantigen presentation. In the future, these new bioinformatics approaches are highly likely to influence precision medicine-based decision making for the use of immunotherapies in virally driven cancers.

Gut microbial diversity and genus-level differences identified in cervical cancer patients versus healthy controls

OBJECTIVES

The aim of this study was to characterize variation in the gut microbiome of women with locally advanced cervical cancer and compare it to healthy controls.

METHODS

We characterized the 16S rDNA fecal microbiome in 42 cervical cancer patients and 46 healthy female controls. Shannon diversity index (SDI) was used to evaluate alpha (within sample) diversity. Beta (between sample) diversity was examined using principle coordinate analysis (PCoA) of unweighted Unifrac distances. Relative abundance of microbial taxa was compared between samples using Linear Discriminant Analysis Effect Size (LEfSe).

RESULTS

Within cervical cancer patients, bacterial alpha diversity was positively correlated with age (p = 0.22) but exhibited an inverse relationship in control subjects (p < 0.01). Alpha diversity was significantly higher in cervical cancer patients as compared to controls (p < 0.05), though stratification by age suggested this relationship was restricted to older women (>50 years; p < 0.01). Beta diversity (unweighted Unifrac; p < 0.01) also significantly differed between cervical cancer patients and controls. Based on age- and race-adjusted LEfSe analysis, multiple taxa significantly differed between cervical cancer patients and controls. Prevotella, Porphyromonas, and Dialister were significantly enriched in cervical cancer patients, while Bacteroides, Alistipes and members of the Lachnospiracea family were significantly enriched in healthy subjects.

CONCLUSION

Our study suggests differences in gut microbiota diversity and composition between cervical cancer patients and controls. Associations within the gut microbiome by age may reflect etiologic/clinical differences. These findings provide rationale for further study of the gut microbiome in cervical cancer.

High Level Expression of MHC-II in HPV+ Head and Neck Cancers Suggests that Tumor Epithelial Cells Serve an Important Role as Accessory Antigen Presenting Cells

High-risk human papillomaviruses (HPVs) are responsible for a subset of head and neck squamous cell carcinomas (HNSCC). Expression of class II major histocompatibility complex (MHC-II) is associated with antigen presenting cells (APCs). During inflammation, epithelial cells can be induced to express MHC-II and function as accessory APCs. Utilizing RNA-seq data from over 500 HNSCC patients from The Cancer Genome Atlas, we determined the impact of HPV-status on the expression of MHC-II genes and related genes involved in their regulation, antigen presentation, and T-cell co-stimulation. Expression of virtually all MHC-II genes was significantly upregulated in HPV+ carcinomas compared to HPV- or normal control tissue. Similarly, genes that encode products involved in antigen presentation were also significantly upregulated in the HPV+ cohort. In addition, the expression of CIITA and RFX5-regulators of MHC-II-were significantly upregulated in HPV+ tumors. This coordinated upregulation of MHC-II genes was correlated with higher intratumoral levels of interferon-gamma in HPV+ carcinomas. Furthermore, genes that encode various co-stimulatory molecules involved in T-cell activation and survival were also significantly upregulated in HPV+ tumors. Collectively, these results suggest a previously unappreciated role for epithelial cells in antigen presentation that functionally contributes to the highly immunogenic tumor microenvironment observed in HPV+ HNSCC.

Papillomavirus Immune Evasion Strategies Target the Infected Cell and the Local Immune System

Persistent infection with human papillomavirus (HPV) initiates ~5% of all human cancers, and particularly cervical and oropharyngeal cancers. HPV vaccines prevent HPV infection, but do not eliminate existing HPV infections. Papillomaviruses induce hyperproliferation of epithelial cells. In this review we discuss how hyperproliferation renders epithelial cells less sensitive to immune attack, and impacts upon the efficiency of the local immune system. These observations have significance for the design of therapeutic HPV cancer immunotherapies.

HPV-16 Infection Is Associated with a High Content of CD39 and CD73 Ectonucleotidases in Cervical Samples from Patients with CIN-1

The development of cervical cancer (CeCa) is associated with high-risk human papilloma virus (HR-HPV) infections, mainly HPV-16, which is present in more than 50% of cases. The presence of immunosuppressive factors in the early stages of the disease is also strongly linked to CeCa progression. In this context, it is unknown whether ectonucleotidases CD39 and CD73, which are involved in the production of adenosine (Ado) that suppresses the specific antitumor immune response, are present in precursor lesions of CeCa. In this pilot study, we analyzed the presence of CD39 and CD73 and their capacity to generate Ado in 25 cervical samples from patients with grade 1 cervical intraepithelial neoplasms (CIN-1) and 25 samples from normal donors (NDs) free of HPV infection. Cells obtained from cervical samples of CIN-1 patients positive for HPV-16 showed higher CD39 and CD73 contents compared to samples obtained from CIN-1 patients negative for HPV-16 and NDs. Interestingly, solubilized cervical mucus from these patients also showed higher contents of soluble CD39 and CD73, which were associated with a greater capacity to produce Ado from the hydrolysis of adenosine triphosphate (ATP) and adenosine monophosphate (AMP). In addition, serum samples of these patients showed higher levels of TGF-β than those of CIN-1 patients negative for HPV-16 and ND. These results suggest that persistent infection with HR-HPV, mostly HPV-16, in CIN-1 patients may promote the expression of CD39 and CD73 through the production of TGF-β in precursor lesions to generate an immunosuppressive microenvironment and allow its progression to CeCa.

Screening for HPV infection in exfoliated cervical cells of women from different ethnic groups in Yili, Xinjiang, China

We investigated the infection status and genotype distribution of human papillomavirus (HPV) in women of different ages and various ethnic groups in the Yili region, Xinjiang, China. We checked the HPV genotypes of 3,445 samples of exfoliated cervical cells using the PCR–reverse dot blot method. The total infection rate of HPV was 25.60% (882/3,445). The ethnic stratification showed that the infection rates were 22.87% (196/857) in Uygur, 21.55% (122/566) in Kazak, and 27.89% (564/2,022) in Han individuals. The most prevalent high-risk genotypes were HPV16, HPV52, and HPV53 in Uygur and Kazak and HPV16, HPV52, and HPV58 in Han ethnic groups. The age stratification showed that the infection rates in Han, Uygur, and Kazak women were up to 40.9% (61/149) in those aged 26–30 years, 41.5% (22/53) in those over 61 years old, and 30.2% (29/96) in those 46–50 years old, respectively. Therefore, HPV infection and HPV genotype distribution varied among the different age groups of the three ethnic groups.

Analysis of Class I Major Histocompatibility Complex Gene Transcription in Human Tumors Caused by Human Papillomavirus Infection

Oncoproteins from high-risk human papillomaviruses (HPV) downregulate the transcription of the class I major histocompatibility complex (MHC-I) antigen presentation apparatus in tissue culture model systems. This could allow infected or transformed cells to evade the adaptive immune response. Using data from over 800 human cervical and head &amp; neck tumors from The Cancer Genome Atlas (TCGA), we determined the impact of HPV status on the mRNA expression of all six MHC-I heavy chain genes, and the β2 microglobulin light chain. Unexpectedly, these genes were all expressed at high levels in HPV positive (HPV+) cancers compared with normal control tissues. Indeed, many of these genes were expressed at significantly enhanced levels in HPV+ tumors. Similarly, the transcript levels of several other components of the MHC-I peptide-loading complex were also high in HPV+ cancers. The coordinated expression of high mRNA levels of the MHC-I antigen presentation apparatus could be a consequence of the higher intratumoral levels of interferon γ in HPV+ carcinomas, which correlate with signatures of increased infiltration by T- and NK-cells. These data, which were obtained from both cervical and oral tumors in large human cohorts, indicates that HPV oncoproteins do not efficiently suppress the transcription of the antigen presentation apparatus in human tumors.

The human papillomavirus E7 oncoprotein as a regulator of transcription

High-risk human papillomaviruses (HPVs) encode oncoproteins which manipulate gene expression patterns in the host keratinocytes to facilitate viral replication, regulate viral transcription, and promote immune evasion and persistence. In some cases, oncoprotein-induced changes in host cell behavior can cause progression to cancer, but a complete picture of the functions of the viral oncoproteins in the productive HPV life cycle remains elusive. E7 is the HPV-encoded factor most responsible for maintaining cell cycle competence in differentiating keratinocytes. Through interactions with dozens of host factors, E7 has an enormous impact on host gene expression patterns. In this review, we will examine the role of E7 specifically as a regulator of transcription. We will discuss mechanisms of regulation of cell cycle-related genes by E7 as well as genes involved in immune regulation, growth factor signaling, DNA damage responses, microRNAs, and others pathways. We will also discuss some unanswered questions about how transcriptional regulation by E7 impacts the biology of HPV in both benign and malignant conditions.

The Interaction Between Human Papillomaviruses and the Stromal Microenvironment

Human papillomaviruses (HPVs) are small, double-stranded DNA viruses that replicate in stratified squamous epithelia and cause a variety of malignancies. Current efforts in HPV biology are focused on understanding the virus-host interactions that enable HPV to persist for years or decades in the tissue. The importance of interactions between tumor cells and the stromal microenvironment has become increasingly apparent in recent years, but how stromal interactions impact the normal, benign life cycle of HPVs, or progression of lesions to cancer is less understood. Furthermore, how productively replicating HPV impacts cells in the stromal environment is also unclear. Here we bring together some of the relevant literature on keratinocyte-stromal interactions and their impacts on HPV biology, focusing on stromal fibroblasts, immune cells, and endothelial cells. We discuss how HPV oncogenes in infected cells manipulate other cells in their environment, and, conversely, how neighboring cells may impact the efficiency or course of HPV infection.

Targeting of HPV-16+ Epithelial Cancer Cells by TCR Gene Engineered T Cells Directed against E6

PURPOSE

The E6 and E7 oncoproteins of HPV-associated epithelial cancers are in principle ideal immunotherapeutic targets, but evidence that T cells specific for these antigens can recognize and kill HPV(+) tumor cells is limited. We sought to determine whether TCR gene engineered T cells directed against an HPV oncoprotein can successfully target HPV(+) tumor cells.

EXPERIMENTAL DESIGN

T-cell responses against the HPV-16 oncoproteins were investigated in a patient with an ongoing 22-month disease-free interval after her second resection of distant metastatic anal cancer. T cells genetically engineered to express an oncoprotein-specific TCR from this patient's tumor-infiltrating T cells were tested for specific reactivity against HPV(+) epithelial tumor cells.

RESULTS

We identified, from an excised metastatic anal cancer tumor, T cells that recognized an HLA-A*02:01-restricted epitope of HPV-16 E6. The frequency of the dominant T-cell clonotype from these cells was approximately 400-fold greater in the patient's tumor than in her peripheral blood. T cells genetically engineered to express the TCR from this clonotype displayed high avidity for an HLA-A*02:01-restricted epitope of HPV-16, and they showed specific recognition and killing of HPV-16(+) cervical, and head and neck cancer cell lines.

CONCLUSIONS

These findings demonstrate that HPV-16(+) tumors can be targeted by E6-specific TCR gene engineered T cells, and they provide the foundation for a novel cellular therapy directed against HPV-16(+) malignancies, including cervical, oropharyngeal, anal, vulvar, vaginal, and penile cancers.

High-risk human papillomavirus targets crossroads in immune signaling

Persistent infections with a high-risk type human papillomavirus (hrHPV) can progress to cancer. High-risk HPVs infect keratinocytes (KCs) and successfully suppress host immunity for up to two years despite the fact that KCs are well equipped to detect and initiate immune responses to invading pathogens. Viral persistence is achieved by active interference with KCs innate and adaptive immune mechanisms. To this end hrHPV utilizes proteins encoded by its viral genome, as well as exploits cellular proteins to interfere with signaling of innate and adaptive immune pathways. This results in impairment of interferon and pro-inflammatory cytokine production and subsequent immune cell attraction, as well as resistance to incoming signals from the immune system. Furthermore, hrHPV avoids the killing of infected cells by interfering with antigen presentation to antigen-specific cytotoxic T lymphocytes. Thus, hrHPV has evolved multiple mechanisms to avoid detection and clearance by both the innate and adaptive immune system, the molecular mechanisms of which will be dealt with in detail in this review.

Immune therapy for human papillomaviruses-related cancers

Human papillomaviruses (HPVs) are a large family of double strand DNA viruses comprising more than 180 types. Infection with HPV is very common and it is associated with benign and malignant proliferation of skin and squamous mucosae. Many HPVs, considered low-risk such as HPV 6 and 11, produce warts; while high-risk viruses, such as HPVs 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, and 58, induce tumors. About 5% of all cancers in men and women are associated with HPV infection. Because there are not antiviral drugs for HPV infection, current therapies for low-risk HPV infections involve physical removal of the lesion by cryotherapy, trichloracetic acid, laser, or surgical removal. Surgical procedures are effective in the treatment of pre-cancerous lesions, however after these procedures, many recurrences appear due to new re-infections, or to failure of the procedure to eliminate the HPV. In addition, HPV can inhibit recognition of malignant cells by the immune system, leading to the development of cancer lesions. When this occurs, radiotherapy and chemotherapy are then used. Unfortunately, about 50% of the HPV-cancer patients still die. In the past decade, a better knowledge of the natural history of the virus-host interaction and of the immune response against this viral infection has brought new therapeutic strategies geared to modulate the immune system to generate an efficient virus-specific cytotoxic response. Novel HPV protein-expressing vaccines have shown some significant clinical efficacy and systemic HPV-specific cytotoxic T cell responses. This review will describe the current status of the several therapeutic strategies used to treat HPV-induced lesions, and discuss the various new therapies now being tested.

The papillomavirus E7 proteins

E7 is an accessory protein that is not encoded by all papillomaviruses. The E7 amino terminus contains two regions of similarity to conserved regions 1 and 2 of the adenovirus E1A protein, which are also conserved in the simian vacuolating virus 40 large tumor antigen. The E7 carboxyl terminus consists of a zinc-binding motif, which is related to similar motifs in E6 proteins. E7 proteins play a central role in the human papillomavirus life cycle, reprogramming the cellular environment to be conducive to viral replication. E7 proteins encoded by the cancer-associated alpha human papillomaviruses have potent transforming activities, which together with E6, are necessary but not sufficient to render their host squamous epithelial cell tumorigenic. This article strives to provide a comprehensive summary of the published research studies on human papillomavirus E7 proteins.