Serological and T-helper cell responses to human papillomavirus type 16 L1 in women with cervical dysplasia or cervical carcinoma and in healthy controls

Antibody response to human papillomavirus vaccination and natural exposure in individuals with Fanconi Anemia

Fanconi anemia (FA) is a rare genetic disorder associated with predisposition to head and neck and gynecological squamous cell cancers. In the general population, these cancers are commonly linked to human papillomavirus (HPV) infection. Antibodies to natural HPV infection and HPV vaccination were evaluated in 63 individuals with FA while considering host immune factors. Approximately 30% of reportedly unvaccinated participants were seropositive (HPV6-38%, HPV11-25%, HPV16-26%, and HPV18-26%). Seropositivity was significantly associated with having had sex regardless of age (p=.007). Most participants showed seropositivity after HPV vaccination (HPV6-100%, HPV11-100%, HPV16-100% and HPV18-92%). Interestingly, titers for all 4 subtypes were significantly lower in the post-hematopoietic stem cell transplant (HSCT) participants compared to those who received the vaccine, but had not undergone HSCT (HPV6-p=.030, HPV11-p=.003, HPV16-p=.018, HPV18-p=<.001). It is unclear if these titers sufficiently protect from new infection since protective serologic cut offs have not yet been defined for the HPV vaccine. Individual immune functions were not associated with HPV seropositivity, however, underlying heterogeneous immune deficiency may explain higher rates of seropositivity in our younger unvaccinated participants (age 4-13 years). To better measure the efficacy of HPV vaccination in those with FA and other immune-compromised or cancer-prone disorders, future well-controlled vaccine studies are required.

T-cell responses to human papillomavirus type 16 among women with different grades of cervical neoplasia

Infection with high-risk genital human papillomavirus (HPV) types is a major risk factor for the development of cervical intraepithelial neoplasia (CIN) and invasive cervical carcinoma. The design of effective immunotherapies requires a greater understanding of how HPV-specific T-cell responses are involved in disease clearance and/or progression. Here, we have investigated T-cell responses to five HPV16 proteins (E6, E7, E4, L1 and L2) in women with CIN or cervical carcinoma directly ex vivo. T-cell responses were observed in the majority (78%) of samples. The frequency of CD4+ responders was far lower among those with progressive disease, indicating that the CD4+ T-cell response might be important in HPV clearance. CD8+ reactivity to E6 peptides was dominant across all disease grades, inferring that E6-specific CD8+ T cells are not vitally involved in disease clearance. T-cell responses were demonstrated in the majority (80%) of cervical cancer patients, but are obviously ineffective. Our study reveals significant differences in HPV16 immunity during progressive CIN. We conclude that the HPV-specific CD4+ T-cell response should be an important consideration in immunotherapy design, which should aim to target preinvasive disease.

Spontaneous regression of grade 3 vulvar intraepithelial neoplasia associated with human papillomavirus-16-specific CD4(+) and CD8(+) T-cell responses

Cell-mediated immunity directed against human papillomavirus 16 (HPV-16) antigens was studied in six patients affected with grade 3 vulvar intraepithelial neoplasia (VIN3, also known as bowenoid papulosis). Five of the patients presented with a chronic and persistent disease that relapsed after destructive treatments. They showed no detectable anti-HPV blood T-cell responses and no T-cell intraepidermal vulvar infiltrate containing both CD4+ and CD8+ lymphocytes. The last patient had a complete clearance of viral lesions, 8 months after disease onset and 2 months after electrocoagulation of <50% of the VIN3 lesions. She showed high frequency anti-E6 and anti-E7 effector blood T cells by ex vivo ELISpot-IFNgamma assay before clinical regression. Immunohistochemical study of her vulvar biopsy revealed a marked dermal infiltrate containing a majority of CD4+ T lymphocytes and an epidermal infiltrate made up of both CD4(+) and CD8(+) T cells. This seems to be the first evidence of an association between spontaneous regression of VIN3 lesions and HPV-specific T-cell responses detectable in the blood. Hence, an increase of HPV-specific effector T lymphocyte responses by vaccine-based therapeutic strategies might be useful to clear the lesions in bowenoid papulosis disease.

Buccal exposure to human papillomavirus type 16 is a common yet transitory event of childhood

High-risk human papillomaviruses, such as type 16 (HPV-16), are established etiological agents for cervical carcinoma. In most cases, this virus is transmitted sexually, though can also be spread from mother to infant at delivery. We have demonstrated previously a high prevalence ( approximately 52%) of HPV-16 DNA in the mouths of prepubertal children, albeit with low levels of transcription [Rice et al., 2000]. We investigated whether childhood buccal infections with HPV-16 are persistent or transient and whether children became infected through contact with their immediate family members. Two groups of children were selected: one group were all initially HPV-16 E5 DNA-positive in sensitive polymerase chain reaction tests of swabs from their buccal mucosa (n = 20), and the other group consisted of children who were all HPV-16 E5-negative (n = 19). Thirty months later, a second oral swab was collected from each child and tested for HPV DNA. At this second visit, 40% of the HPV-16-positive group had no detectable HPV-16 DNA; conversely, 63% of children who were originally HPV-16-negative had now acquired the virus. Three months later, a third sample was collected from eight children and their immediate families (seven were HPV-16 E5 DNA-positive at the second visit). Amongst the family samples tested, in two families a single previously untested child was HPV-16 DNA-positive. It is concluded that HPV-16 DNA in the oral cavities of children is a transient event and is most probably acquired from their peers.

Human papillomavirus type 16-specific T cell responses and their association with recurrence of cervical disease following treatment

Human papillomavirus type 16 (HPV-16) L1- and E7-specific T cell responses were measured in 58 women with abnormal cervical cytology in a prospective study. On recruitment, patients responded most frequently and with the highest numbers of responding cells to the L1 region aa 311-345 and this response was significantly associated with the presence of cervical disease (P=0.041). Responses to the L1 peptide aa 281-295 were significantly higher in patients with CIN III than in those with HPV/CIN I or CIN II lesions (P=0.027). The E7 region aa 70-98 was the most immunogenic in patients with squamous intraepithelial lesions of the cervix (SIL) but the responses detected were not significantly higher than in patients without SIL. Following treatment, the T cell response profiles of patient groups did not change significantly. However, on analysis of the responses of individual patients with and without recurrent disease on follow-up, significant differences were found. Recurrence of disease was associated with T cell responses to the E7 region aa 70-98 at the patient's first clinic visit (P=0.017). Recurrence of disease was also accompanied by an increase in the total number of L1-specific short-term T cell lines (STLs) at follow-up, whereas absence of disease was accompanied by a decrease in L1-specific STLs. The data also suggested a possible link between E7 70-98-specific responses and acquisition of disease by patients who were previously disease-free. Further studies are warranted to determine whether this response could be useful as a marker of recurrent disease in some patients.

Sexual and non-sexual transmission of human papillomavirus

Benign tumors and lesions of the anogenital tract are caused by human papillomaviruses (HPVs). They are also major risk factors for cervical cancer. Introduction of the polymerase chain reaction (PCR) revealed that HPV infections are much more common among young asymptomatic women than it had been previously suspected. The side-specificity of genital HPVs led to the assumption that HPVs were primarily transmitted by sexual contact. However, since HPVs have been detected in virgins, infants/children and juvenile laryngeal papillomatosis was shown to be caused by these viruses, it became acknowledged that HPVs may be transmitted by other--non-sexual--routes as well. The evidence for sexual and different non-sexual routes of transmission of HPVs will be reviewed here.

Time course of humoral and cell-mediated immune responses to human papillomavirus type 16 in infected women

The time course of cell-mediated and humoral immune responses was elucidated in eight women with human papillomavirus type 16 (HPV-16) infection by performing serial HPV-16 E6 and E7 cytotoxic T-lymphocyte (CTL) assays and HPV-16 virus-like particle (VLP) antibody analyses. Four subjects had a single incident of HPV-16 DNA detection, and four subjects had two periods of HPV-16 DNA detection. In two of the women in the latter group, the second episode of HPV-16 detection occurred in the presence of high titers of HPV-16 VLP antibody, bringing into question the protective role of humoral immunity in preventing repeated infection. However, all four subjects rapidly became HPV-16 DNA negative following the second detection of HPV-16 DNA, suggesting the presence of immunological memory. In addition, one subject rapidly became negative for HPV-16 DNA despite having no evidence of CTL or VLP antibody response prior to the second HPV-16 DNA detection, suggesting the presence of immunological responses at an undetectable level. Overall, seven of eight subjects (88%) had detectable HPV-16 E6 and/or E7 CTL responses and seven of eight women (88%) had detectable HPV-16 VLP antibody responses.

Single-cell cytokine analysis allows detection of cervical T-cell responses against human papillomavirus type 16 L1 in women infected with genital HPV

Specific types of human papillomavirus (HPV) are known to play a causal role in the development of cervical cancer, with human papillomavirus type 16 (HPV-16) identified as the predominant type. Despite this, little is known about cervical immune responses to this pathogen. The aim of this study was to assess the feasibility of cervical cytobrush sampling and single-cell cytokine staining to investigate cervical lymphocyte-specific cytokine responses to HPV-16 antigens. Of eighteen women recruited into the study, five were HPV DNA positive at the cervix (current exposure) and a further five had circulating antibodies to HPV-16 (previous exposure). Cervical lymphocytes, isolated from the five HPV DNA-positive women, two HPV DNA-negative controls, and one woman with circulating HPV-16 antibodies were assessed for HPV-specific responses using intracellular staining for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). We demonstrate that both CD4(+) and CD8(+) cervical T lymphocytes, harvested from noninfected and infected subjects, produce these cytokines in response to nonspecific stimulation. However, antigen-specific (HPV-16 L1) IFN-gamma production by CD4(+) and CD8(+) cervical T lymphocytes is only detectable in women exposed currently or previously to HPV-16. This is the first time that antigen-specific cytokine responses of mucosal lymphocytes, obtained from a site of HPV infection, have been demonstrated. This finding clearly illustrates the use of intracellular cytokine staining for investigation of low precursor frequency single-cell antigen-specific responses in lymphocytes harvested from mucosal sites with HPV infection.

Chronic immune activation and inflammation in the pathogenesis of AIDS and cancer

Infection with the human immunodeficiency virus (HIV) invariably leads to the development of acquired immunodeficiency syndrome (AIDS) in most infected humans, yet does so rarely, if at all, in HIV-infected chimpanzees. The differences between the two species are not due to differences in cellular receptors or an inability of the chimpanzee to be infected, but rather to the lack of pan-immune activation in the infected primate. This results in reduced apoptotic death in CD4+ T-helper lymphocytes and a lower viral load. In humans the degree of chronic immune activation correlates with virus load and clinical outcome with high immune activation leading to high viral loads and the more rapid progression to AIDS and death. The type of immune perturbation seen in HIV-associated AIDS is similar to that of chronic graft-versus-host disease (GVHD) where reduced cell-mediated immune (CMI) responses occur early in the course of the disease and where humoral responses (HI) predominate. A reduced CMI response occurs in a number of chronic infectious diseases, including tuberculosis and leishmaniasis. More recently, it has become increasingly apparent that the CMI response is suppressed in virtually all malignant diseases, including melanoma and colorectal and prostate cancer. This raises the possibility that, as the malignant process develops, the cancer cells evolve to subvert the CMI response. Moreover, the reduced CMI response seen in colorectal cancer (CRC) patients is completely reversed following curative surgery strongly supporting the hypothesis that CRC can suppress the systemic immune response. Wound healing, ovulation, embryo implantation, and fetal growth are all associated with suppressed CMI and neovascularization (the formation of new blood vessels) or angiogenesis (the formation of new blood vessels from an existing vasculature). If unresolved, wound healing results in chronic inflammation, which can give rise to the phenomenon of "scar cancers." Indeed all the chronic inflammatory conditions known to be associated with the subsequent development of malignant disease, including chronic obstructive airway disease (COPD), ulcerative colitis (UC), and asbestosis, give rise to similar proangiogenic, suppressed CMI, and HI-predominant environments. In keeping with this CMI-associated cytokines such as interleukin (IL)-2 and interferon (IFN)-gamma tend to be antiangiogenic, whereas HI cytokines such as IL-6 tend to be proangiogenic. Furthermore, chronic immune activation leads to the synthesis and release of factors such as macrophage inflammatory protein (MIP)-1 that inhibit apoptosis through suppression of p53 activity. The "Golden Triangle" of suppressed CMI, angiogenesis, and reduced apoptosis would provide the ideal environment for the serial mutations to occur that are required for the development of malignant disease. If the observed association is relevant to carcinogenesis, then treatments aimed at reducing the components of these inflammatory conditions may be useful both in the setting of chemoprevention and the therapeutic management of established disease.

Prophylactic and therapeutic vaccines for genital papillomavirus infection

The development of potential therapeutic and prophylactic vaccines for human papillomavirus (HPV) infection is a very exciting area of HPV research. There are a number of features of HPV biology that makes the development of a vaccine particularly difficult, although there are several examples of vaccines that have had spectacular success in the prevention of other viral diseases. Our poor understanding of the immune response to HPV infection is the first problem. We do not understand the mechanism by which spontaneous clearing of warts is generated and therefore cannot particularly target this pathway in the development of a vaccine. Furthermore, there is no in vitro culture system nor an animal model for HPV. Another problem is that there is no ready source of live virus that might be exploited for a live attenuated viral vaccine, such as was used with poliovirus. Although most other viruses spend a portion of their life cycle in the systemic circulation where they are vulnerable to neutralizing antibodies, HPV remain exclusively in the epithelium and thus antibodies must transverse the basement membrane and reach the other layers of the skin or mucosa to be effective in preventing infection. Significant progress is being made in the development of potential vaccine candidates despite these and other confounding factors.

Immunology of human papillomavirus infection in lower genital tract neoplasia

Despite its being a relatively common virus, the study of human papillomavirus infection has lagged behind that of other viruses. Human papillomaviruses do not provoke strong systemic antibody or T-cell responses. Furthermore, the majority of those infected do not display clinical symptoms and are able to clear the virus by unknown mechanisms. In the last decade, however, research into human papillomavirus immunology has blossomed, for two main reasons. First, there is strong circumstantial evidence that the immune system can control papillomavirus infection, since the prevalence of human papillomavirus-associated neoplasia is increased in immunocompromised individuals. Second, the strong association between human papillomavirus infection and cervical cancer has led to attempts to develop prophylactic or therapeutic vaccines. In this chapter, our current knowledge of human papillomavirus immune responses will be reviewed, and how this relates to clinical practice will be discussed.

High prevalence of human papillomavirus type 16 infection among children

Infection with high-risk human papillomaviruses (HPV), is the most significant risk factor for cervical cancer and it may be possible to prevent this malignancy by immunisation. Before immunisation programmes can be designed, however, it is necessary to know the age of acquisition and all routes of infection for these viruses. Sexual transmission is well documented and vertical transmission has also been demonstrated, although the frequency of transmission remains controversial. We previously showed that vertical transmission frequently results in persistent infection, and now present data on the prevalence of HPV-16 DNA (the most prevalent high-risk HPV type) in healthy children. Buccal samples from 267 healthy children aged 3-11 years were tested for HPV DNA by generic PCR (MY09/MY11), and a HPV-16 specific nested PCR. Reverse transcriptase (RT)-PCR was used to determine the prevalence of transcriptionally active HPV-16 infection in a subset of children. HPV-16 DNA was detected by nested PCR in 138 of 267 (51.7%) samples, whereas HPV DNA was detected in only 45 (16.8%) specimens by generic PCR, that has a lower analytical sensitivity. There were no significant differences in prevalence according to age or sex. Early region mRNA was detected by RT-PCR in six (11.3%) of 53 HPV-16 E5 DNA positive samples. HPV-16 E5 DNA sequences from 10 children confirmed the identity of the sequences detected and identified 13 HPV-16 variants.

Seroresponses to human papillomavirus types 16, 18, 31, 33, and 45 virus-like particles in South African women with cervical cancer and cervical intraepithelial neoplasia

The aim of the study was to determine the prevalence of antibodies to human papillomavirus (HPV) types 16, 18, 31, 33, and 45 in woman in Cape Town with cervical intraepithelial neoplasia (CIN) (n = 95), cervical cancer (n = 40), female blood donors (n = 95) and children (n = 110). The enzyme-linked immunosorbent assay (ELISA) made use of baculovirus synthesised HPV virus like particles (VLPs) as antigen. Antibodies to at least one HPV type were detected in sera from 75% of cancer patients, 71.6% of CIN patients, 44.2% of blood donors and 27.3% of children. Sera from 95 women with CIN were compared with age-matched female blood donors. There was a significant association of seropositivity to VLP-16 (P = 0.006) and VLP-45 (P = 0.008) with CIN compared with the blood donors. There was also a significant difference in the seropositivity of women with CIN to any of the five virus-like particle (VLP) types compared to the blood donors (P = 0.0002: OR = 3.2). Thirty-nine of sixty-nine (56.5%) women with CIN were found to be HPV-16 DNA positive. The average age of women in this group that were VLP-16 seropositive was 34 years and those found to be VLP-16 seronegative was 52 years of age. Antibodies to all five VLP types were detected in these populations, thus an ideal vaccine should induce protection from infection by a wide range of HPV types.

The relationship between angiogenesis and the immune response in carcinogenesis and the progression of malignant disease

Recent studies have demonstrated that angiogenesis and suppressed cell-mediated immunity (CMI) play a central role in the pathogenesis of malignant disease facilitating tumour growth, invasion and metastasis. In the majority of tumours, the malignant process is preceded by a pathological condition or exposure to an irritant which itself is associated with the induction of angiogenesis and/or suppressed CMI. These include: cigarette smoking, chronic bronchitis and lung cancer; chronic oesophagitis and oesophageal cancer; chronic viral infections such as human papilloma virus and ano-genital cancers, chronic hepatitis B and C and hepatocellular carcinoma, and Epstein-Barr virus (EBV) and lymphomas; chronic inflammatory conditions such as Crohn's disease and ulcerative colitis and colorectal cancer; asbestos exposure and mesothelioma and excessive sunlight exposure/sunburn and malignant melanoma. Chronic exposure to growth factors (insulin-like growth factor-I in acromegaly), mutations in tumour suppressor genes (TP53 in Li Fraumeni syndrome) and long-term exposure to immunosuppressive agents (cyclosporin A) may also give rise to similar environments and are associated with the development of a range of solid tumours. The increased blood supply would facilitate the development and proliferation of an abnormal clone or clones of cells arising as the result of: (a) an inherited genetic abnormality; and/or (b) acquired somatic mutations, the latter due to local production and/or enhanced delivery of carcinogens and mutagenic growth factors. With progressive detrimental mutations and growth-induced tumour hypoxia, the transformed cell, to a lesser or greater extent, may amplify the angiogenic process and CMI suppression, thereby facilitating further tumour growth and metastasis. There is accumulating evidence that long-term treatment with cyclo-oxygenase inhibitors (aspirin and indomethacin), cytokines such as interferon-alpha, anti-oestrogens (tamoxifen and raloxifene) and captopril significantly reduces the incidence of solid tumours such as breast and colorectal cancer. These agents are anti-angiogenic and, in the case of aspirin, indomethacin and interferon-alpha have proven immunomodulatory effects. Collectively these observations indicate that angiogenesis and suppressed CMI play a central role in the development and progression of malignant disease.

The use of vaccines in treating cervical cancer: present status and future prospects

HPV types are carcinogenic agents in cervical cancer. This view is supported by epidemiological and biological evidence. The oncogenic products and capsid proteins of high risk HPV types are potential targets against which effective immunity may be generated by vaccination. Both therapeutic and prophlylactic immunisation are potential strategies to deal with the widespread problem of HPV infection and possibly established cervical neoplasia. Clinical trials are now underway to evaluate candidate vaccines.

Prospects for human papillomavirus vaccine development: emerging HPV vaccines

This review concentrates on recent advances in human papillomavirus vaccine development. Strategies for prophylactic HPV subunit vaccines utilizing recombinantly synthesized, immunogenic virus-like particles are discussed. Therapeutic strategies focusing on the induction of cell-mediated immunity and gene manipulation for the treatment of established HPV-associated disease are also reviewed.

HPV detection in children prior to sexual debut

Knowledge of the epidemiology of infection with human papillomavirus (HPV) in childhood is important, since HPV infection early in life could represent a risk factor for later development of anogenital cancer. A random sample of Danish children aged 0 to 17 years was tested for the presence of HPV in the anal region and the oral cavity by the polymerase chain reaction using a consensus HPV L1 primer. Only 4 of 249 anal beta-globin-positive samples and one of 392 oral beta-globin-positive samples were HPV-positive. All HPV-positive samples were of unknown types. We conclude that the prevalence of anogenital HPV infection in childhood is very low indeed and that the oral cavity does not seem to act as a reservoir for HPV infection in childhood. This indicates that anogenital types of HPV are not transmitted to any measureable degree by non-sexual routes and further supports the notion that HPV infection takes place mainly later in life.