Papillomaviruses: a correlation between immune evasion and oncogenicity?

The Effectiveness of Chemical Cautery and Electrosurgery on Anogenital Wart: Systematic Review

Introduction

Anogenital warts (AGW) is one of the sexually transmitted infections (STIs) caused by human papillomavirus (HPV). Treatment modalities of AGW yield low clearance and recurrence rate, so that chemical cautery with trichloroacetic acid (TCA) and electrosurgery are widely used to remove the lesions without any severe side effects.

Objective

To investigate the efficacy of chemical cautery with TCA and electrosurgery in AGW based on clinical trials or case series.

Methods

The systematic review was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) but not registered to the International Prospective Register of Systematic Review (PROSPERO). To acquire proper and accurate information from relevant literature, two databases PubMed and the Cochrane Library were searched from January 2013 to March 2023.

Results

Thirteen studies were included in this systematic review, comprising seven articles on chemical cautery and six electrosurgery articles. The highest cure rate of chemical cautery with TCA was 94.1% while electrosurgery was 100%. A relatively low recurrence rate during 1 year follow-up was observed in electrosurgery with 14.6%, whereas the chemical cautery was 27.6%.

Conclusion

Electrosurgery for AGW treatment had higher cure rate with lower recurrence rate compared to chemical cautery with TCA. Numerous adverse effects of electrosurgery were reported include bleeding and scar formation as high risk of HPV infection.

Oral Infection by Mucosal and Cutaneous Human Papillomaviruses in the Men Who Have Sex with Men from the OHMAR Study

Both mucosal and cutaneous Human Papillomaviruses (HPVs) can be detected in the oral cavity, but investigations regarding the epidemiology of cutaneous HPVs at this site are scarce. We assessed mucosal (alpha) and cutaneous (beta and gamma) HPV infection in oral samples of HIV-infected and uninfected men who have sex with men (MSM). Oral rinse-and-gargles were collected from 310 MSM. Alpha HPVs were detected using the Linear Array, whereas beta and gamma HPVs were detected using multiplex PCR and Luminex technology. An amplicon-based next-generation sequencing (NGS) protocol was applied to a subset of samples collected from 30 HIV-uninfected and 30 HIV-infected MSM. Beta HPVs were significantly more common than alpha types (53.8% vs. 23.9% for HIV-infected subjects, p < 0.0001; 50.3% vs. 17.1% for HIV-uninfected subjects, p < 0.0001). Gamma HPVs were also frequently detected (30.8% and 25.9% in HIV-infected and uninfected MSM, respectively). NGS produced 2,620,725 reads representative of 146 known HPVs (16 alpha-PVs, 53 beta-PVs, 76 gamma-PVs, one unclassified) and eight putative new HPVs, taxonomically assigned to the beta genus. The oral cavity contains a wide spectrum of HPVs, with beta types representing the predominant genus. The prevalence of beta and gamma HPVs is high even in immunorestored HIV-infected individuals. NGS confirmed the abundance of cutaneous HPVs and identified some putative novel beta HPVs. This study confirms that cutaneous HPVs are frequently present at mucosal sites and highlights that their pathological role deserves further investigation since it may not be limited to skin lesions.

High-risk human papillomavirus testing as a primary screening for cervical cancer: position statement by the Korean Society of Obstetrics and Gynecology and the Korean Society of Gynecologic Oncology

Based on emerging data and current knowledge regarding high-risk human papillomavirus (hrHPV) testing as a primary screening for cervical cancer, the Korean Society of Obstetrics and Gynecology and the Korean Society of Gynecologic Oncology support the following scientific facts:

• Compared to cytology, hrHPV screening has higher sensitivity and detects more cases of high-grade cervical intraepithelial neoplasia.

• Qualified hrHPV testing can be considered as an alternative primary screening for cervical cancer to the current cytology method.

• The starting age of primary hrHPV screening should not be before 25 years because of possible overtreatment in this age, which has a high human papillomavirus (HPV) prevalence but rarely progresses to cancer. The screening interval should be no sooner than every 3 years and no longer than every 5 years.

• Before the introduction of hrHPV screening in Korea, research into comparative effectiveness of primary hrHPV screening for cervical cancer should be conducted to determine the appropriate HPV assay, starting age, and screening interval.

How Human Papillomavirus Replication and Immune Evasion Strategies Take Advantage of the Host DNA Damage Repair Machinery

The DNA damage response (DDR) is a complex signalling network activated when DNA is altered by intrinsic or extrinsic agents. DDR plays important roles in genome stability and cell cycle regulation, as well as in tumour transformation. Viruses have evolved successful life cycle strategies in order to ensure a chronic persistence in the host, virtually avoiding systemic sequelae and death. This process promotes the periodic shedding of large amounts of infectious particles to maintain a virus reservoir in individual hosts, while allowing virus spreading within the community. To achieve such a successful lifestyle, the human papilloma virus (HPV) needs to escape the host defence systems. The key to understanding how this is achieved is in the virus replication process that provides by itself an evasion mechanism by inhibiting and delaying the host immune response against the viral infection. Numerous studies have demonstrated that HPV exploits both the ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and rad3-related (ATR) DDR pathways to replicate its genome and maintain a persistent infection by downregulating the innate and cell-mediated immunity. This review outlines how HPV interacts with the ATM- and ATR-dependent DDR machinery during the viral life cycle to create an environment favourable to viral replication, and how the interaction with the signal transducers and activators of transcription (STAT) protein family and the deregulation of the Janus kinase (JAK)-STAT pathways may impact the expression of interferon-inducible genes and the innate immune responses.

Risk factors for cancer in the Australian Aboriginal and Torres Strait Islander population: a systematic review

Cancer incidence in the Australian Aboriginal and Torres Strait Islander population is higher and survival lower compared with non-Indigenous Australians. A proportion of these cancers are potentially preventable if factors associated with carcinogenesis are known and successfully avoided. We conducted a systematic review of the published literature to examine risk factors for cancer in the Australian Aboriginal and Torres Strait Islander population. Electronic databases Medline, Web of Science and the Australian Aboriginal and Torres Strait Islander Health Bibliographic Index were searched through August 2014 using broad search terms. Studies reporting a measure of association between a risk factor and any cancer site in the Australian Aboriginal and Torres Strait Islander population were eligible for inclusion. Ten studies (1991-2014) were identified, mostly with small sample sizes, showing marked heterogeneity in terms of methods used to assess exposure and capture outcomes, and often using descriptive comparative analyses. Relatively young (as opposed to elderly) and geographically remote Aboriginal and Torres Strait Islanders were found to be at increased risk for selected cancers while most modifiable lifestyle and behavioural risk factors were rarely assessed. Further studies examining associations between potential risk factors and cancer will help define public health policy for cancer prevention in the Australian Aboriginal and Torres Strait Islander population.

Anal human papillomavirus in HIV-uninfected men who have sex with men: incidence and clearance rates, duration of infection, and risk factors

Little is known regarding the natural history of anal human papillomavirus (HPV) infection. We aimed to evaluate incidence and clearance rates, their risk factors, and duration of anal HPV infection in HIV-uninfected men who have sex with men (MSM). A longitudinal study was conducted. Anal samples were analysed using the Linear Array HPV Genotyping test. Incidence and clearance rates, and corresponding risk factors, were estimated using a two-state Markov model. Overall, 155 MSM (median age 33.4 years) attending the largest sexually transmitted infection (STI) centre in Rome, Italy, were followed for a median of 12.2 months (Q1-Q3: 7.0-18.1). Incidence and clearance rates for any HPV were 85.6 (95% CI: 58.4-125.4) and 35.6 (95% CI: 24.7-51.5) × 1000 person-months, respectively; the median duration of infection was 9.4 months (Q1-Q3: 7.5-12.1). Receptive anal sex emerged as the only risk factor for the acquisition of any HPV (Hazard Ratio, HR = 2.65, 95% CI: 1.16-6.06). The incidence rates for carcinogenic and non-carcinogenic types were 42.3 (95% CI: 29.2-61.4) and 29.2 (95% CI: 19.5-43.7) × 1000 person-months, respectively (p = 0.13); their clearance rates were 62.9 (95% CI: 45.1-87.7) and 65.7 (95% CI: 47.4-91.0) × 1000 person-months, respectively (p = 0.83). HPV16 showed the lowest clearance rate among carcinogenic types (59.7 × 1000 person-months), and a duration of infection of 16.8 months. In conclusion, a higher incidence rate was observed for carcinogenic compared to non-carcinogenic HPV types, although the difference was not significant. HPV16 emerged as the type with the longest duration of infection and the lowest clearance rate among carcinogenic types.

Immunotherapy of HPV-associated cancer: DNA/plant-derived vaccines and new orthotopic mouse models

Under the optimistic assumption of high-prophylactic HPV vaccine coverage, a significant reduction of cancer incidence can only be expected after decades. Thus, immune therapeutic strategies are needed for persistently infected individuals who do not benefit from the prophylactic vaccines. However, the therapeutic strategies inducing immunity to the E6 and/or E7 oncoprotein of HPV16 are more effective for curing HPV-expressing tumours in animal models than for treating human cancers. New strategies/technologies have been developed to improve these therapeutic vaccines. Our studies focussed on preparing therapeutic vaccines with low-cost technologies by DNA preparation fused to either plant-virus or plant-toxin genes, such as saporin, and by plant-produced antigens. In particular, plant-derived antigens possess an intrinsic adjuvant activity that makes these preparations especially attractive for future development. Additionally, discrepancy in vaccine effectiveness between animals and humans may be due to non-orthotopic localization of animal models. Orthotopic transplantation leads to tumours giving a more accurate representation of the parent tumour. Since HPV can cause cancer in two main localizations, anogenital and oropharynx area, we developed two orthotopic tumour mouse models in these two sites. Both models are bioluminescent in order to follow up the tumour growth by imaging and are induced by cell injection without the need to intervene surgically. These models were utilized for immunotherapies with genetic or plant-derived therapeutic vaccines. In particular, the head/neck orthotopic model appears to be very promising for studies combining chemo-radio-immune therapy that seems to be very effective in patients.

Alpha, beta and gamma Human Papillomaviruses in the anal canal of HIV-infected and uninfected men who have sex with men

OBJECTIVES

Anal infection by cutaneous Human Papillomaviruses (HPV) has been rarely investigated. We aimed to assess the prevalence, genotype diversity, and determinants of mucosal (alpha) and cutaneous (beta and gamma) anal HPV infection in men who have sex with men (MSM).

METHODS

Anal samples were collected with a Dacron swab. Alpha HPVs were detected using the Linear Array HPV genotyping test, while beta and gamma HPVs using a PCR combined with Luminex technology.

RESULTS

A total of 609 MSM (437 HIV-uninfected and 172 HIV-infected, most of which were undergoing cART) were enrolled. Alpha, beta, and gamma HPVs were detected in 78.0%, 27.6% and 29.3% of the participants. Only alpha HPV prevalence was significantly higher among HIV-infected compared to uninfected MSM (93.0% vs. 72.1%, p < 0.0001). Beta2 and gamma10 represented the most frequent cutaneous HPV species, with no significant differences between HIV-infected and uninfected individuals. The most common alpha, beta, and gamma genotypes were HPV16, HPV111, HPV121, respectively. Alpha HPV infection was significantly associated with lifetime number of partners, receptive anal sex, and HIV status. Beta and/or gamma HPV infection showed no significant association with HIV status, socio-demographic or sexual behavioral factors.

CONCLUSIONS

A wide spectrum of mucosal and cutaneous HPV types is present in the anal canal. Only mucosal HPV prevalence increased significantly in cases of concomitant HIV infection.

Role of human papillomaviruses in carcinogenesis

The human papillomavirus (HPV) family comprises more than 170 different types that preferentially infect the mucosa of the genitals, upper-respiratory tract, or the skin. The 'high-risk HPV type', a sub-group of mucosal HPVs, is the cause of approximately 5% of all human cancers, which corresponds to one-third of all virus-induced tumours. Within the high-risk group, HPV16 is the most oncogenic type, being responsible for approximatively 50% of all worldwide cervical cancers. Many studies suggest that, in addition to the high-risk mucosal HPV types, certain cutaneous HPVs also have a role in the development of non-melanoma skin cancer (NMSC). Functional studies on the HPV early gene products showed that E6 and E7 play a key role in carcinogenesis. These two proteins use multiple mechanisms to evade host immune surveillance, allowing viral persistence, and to deregulate cell cycle and apoptosis control, thus facilitating the accumulation of DNA damage and ultimately cellular transformation. The demonstration that high-risk HPV types are the etiological agents of cervical cancer allowed the implementation in the clinical routine of novel screening strategies for cervical lesions, as well as the development of a very efficient prophylactic vaccine. Because of these remarkable achievements, there is no doubt that in the coming decades we will witness a dramatic reduction of cervical cancer incidence worldwide.

Role of IL-10 and TGF-β1 in local immunosuppression in HPV-associated cervical neoplasia

Cervical cancer is a worldwide disease that constitutes a significant public health problem, especially in developing countries, not only due to its high incidence but also because the most affected population comprises women who belong to marginalized socio-economic classes. Clinical and molecular research has identified immunological impairment in squamous intraepithelial cervical lesions and cervical cancer patients. Human Papillomavirus (HPV) has several mechanisms for avoiding the immune system: it down-regulates the expression of interferon and upregulates interleukin (IL)-10 and transforming growth factor (TGF)-β1 to produce a local immunosuppressive environment, which, along with altered tumor surface antigens, forms an immunosuppressive network that inhibits the antitumor immune response. In this review we analyzed the available data on several deregulated cellular immune functions in patients with NIC I, NIC II and NIC III and cervical cancer. The effects of immunosuppressive cytokines on innate immune response, T-cell activation and cellular factors that promote tumor cell proliferation in cervical cancer patients are summarized. We discuss the functional consequences of HPV E2, E6, and E7 protein interactions with IL-10 and TGF-β1 promoters in the induction of these cytokines and postulate its effect on the cellular immune response in squamous intraepithelial cervical lesions and cervical cancer patients. This review provides a comprehensive picture of the immunological functions of IL-10 and TGF-β1 in response to HPV in humans.

Tumourigenesis driven by the human papillomavirus type 16 Asian-American e6 variant in a three-dimensional keratinocyte model

Infection with a transforming human papillomavirus (HPV) such as type 16 (of species Alphapapillomavirus 9) causes ano-genital and oral tumours via viral persistence in human squamous cell epithelia. Epidemiological studies showed that the naturally occurring HPV16 Asian-American (AA) variant (sublineage D2/D3) is found more often than the European Prototype (EP) (sublineage A1) in high-grade cervical neoplasia and tumours compared to non-cancer controls. Just three amino acid changes within the early gene, E6, of HPV16 AA have been linked to this augmented tumourigenicity. The AAE6 variant's greater immortalizing and transforming potential over EPE6 has recently been confirmed in retrovirally-transduced keratinocytes expressing the E6 gene only. However, the tumourigenic role of the full-length viral genome of HPV16 has not yet been addressed with regard to these E6 variants. To investigate this process in the context of these two HPV16 E6 genotypes, an organotypic tissue culture model was used to simulate the HPV infectious life cycle. The AAE6 variant demonstrated an enhanced ability over EPE6 to drive the viral life cycle toward tumourigenesis, as evidenced phenotypically—by a more severe grade of epithelial dysplasia with higher proliferation and deregulated differentiation, and molecularly—by high viral oncogene E6 and E7 expression, but lack of productive viral life cycle markers. In contrast, EPE6 had low E6 and E7 but high E1∧E4 expression, indicative of a productive life cycle. We suggest increased viral integration into the host genome for AAE6 as one possible mechanism for these observed differences from EPE6. Additionally, we found downstream effects on immortalization and host innate immune evasion. This study highlights how minor genomic variations in transforming viruses can have a significant affect on their tumourigenic ability.

Dense genotyping of immune-related loci identifies variants associated with clearance of HPV among HIV-positive women in the HIV epidemiology research study (HERS)

Persistent high-risk human papillomavirus (HR-HPV) is a necessary and causal factor of cervical cancer. Most women naturally clear HPV infections; however, the biological mechanisms related to HPV pathogenesis have not been clearly elucidated. Host genetic factors that specifically regulate immune response could play an important role. All HIV-positive women in the HIV Epidemiology Research Study (HERS) with a HR-HPV infection and at least one follow-up biannual visit were included in the study. Cervicovaginal lavage samples were tested for HPV using type-specific HPV hybridization assays. Type-specific HPV clearance was defined as two consecutive HPV-negative tests after a positive test. DNA from participants was genotyped for 196,524 variants within 186 known immune related loci using the custom ImmunoChip microarray. To assess the influence of each single-nucleotide polymorphism (SNP) with HR-HPV clearance, the Cox proportional hazards model with the Wei-Lin-Weissfeld approach was used, adjusting for CD4+ count, low risk HPV (LR-HPV) co-infection, and relevant confounders. Three analytical models were performed: race-specific (African Americans (n = 258), European Americans (n = 87), Hispanics (n = 55), race-adjusted combined analysis, and meta-analysis of pooled independent race-specific analyses. Women were followed for a median time of 1,617 days. Overall, three SNPs (rs1112085, rs11102637, and rs12030900) in the MAGI-3 gene and one SNP (rs8031627) in the SMAD3 gene were associated with HR-HPV clearance (p<10(-6)). A variant (rs1633038) in HLA-G were also significantly associated in African American. Results from this study support associations of immune-related genes, having potential biological mechanism, with differential cervical HR-HPV infection outcomes.

Bovine Papillomavirus: New Insights into an Old Disease

Bovine papillomaviruses (BPVs) are small DNA tumoral viruses able to induce benign cutaneous and/or mucosal epithelial lesions. Generally, the benign tumours affecting the skin or mucosa spontaneously regress, but under special circumstances, the defence system may be overwhelmed, thus leading to cancer, especially in the presence of immunosuppressant and mutagen agents from bracken fern. To date, thirteen different BPV genotypes have been associated with skin and mucosal tumours in cattle, and out of these, only four types (BPV-1, -2, -5 and -13) cross-infect other species. Recent investigations in vivo have revealed new insights into the epidemiology and pathogenesis of this viral infection. This review briefly discusses viral epidemiology, will give data on BPV genome structure and viral genes and will describe the cellular events and new aspects of both cutaneous and mucosal tumours in large ruminants. Finally, some aspects of active immunization will be described.

Differential expression of HPV16 L2 gene in cervical cancers harboring episomal HPV16 genomes: influence of synonymous and non-coding region variations

We tested the hypothesis that (i) synonymous variations within the coding regions, and (ii) variations within the non-coding regions of HPV, influence cervical cancer (CaCx) pathogenesis under the impact of intact HPV16 genomes. Whole genome sequence analysis of HPV16 isolates within 70 CaCx cases and 25 non-malignant samples revealed that synonymous variations were significantly higher within the E6 (p = 0.014), E5 (p = 0.001) and L2 (p = 0.0002) genes of HPV16 isolates within cases, compared to isolates within non-malignant samples. All of the 25 (100%) humanized codons identified within L2 ORF of the samples analyzed, were harbored by CaCx cases, while 8 out of 25 (32%) were harbored by HPV16 positive non-malignant samples (p = 3.87105E-07). L2 (mRNA and protein) expression was evident only among cases with episomal viral genomes and L2 mRNA expression correlated significantly with E2 gene copy numbers suggesting expression from all episomal genomes. Among such cases, Asian American (AA) isolates portrayed all of the humanized codons (100%; 4–6/sample) recorded within L2, which was significantly higher (p = 2.02E-7) compared to the European (E) isolates (22.8%; none or 1–2/sample). Additionally, majority of E variant isolates within cases (54/57; 94.7%) portrayed a variation (T4228C) within the short non-coding region (NCR2) between E5 and L2 genes, which portrays a weak promoter activity specific for L2 mRNA expression. This resulted in loss of 9 out of 14 miRNA binding sites (hsa-miR-548 family), despite the significant overexpression of miR548a-5p and miR548d-5p among such cases (28.64 and 36.25 folds, respectively), in comparison to HPV negative control samples. The findings exemplify the biological relevance of sequence variations in HPV16 genomes and highlight that episomal HPV16 in CaCx cases employ multiple mechanisms to sustain L2 expression, thereby justifying the potential role of L2 in such cancers, as opposed to those harboring viral integration.

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

High risk human Papillomavirus (HPV) types are the major causative agents of cervical cancer. Reduced expression of major histocompatibility complex class I (MHC I) on HPV-infected cells might be responsible for insufficient T cell response and contribute to HPV-associated malignancy. The viral gene product required for subversion of MHC I synthesis is the E7 oncoprotein. Although it has been suggested that high and low risk HPVs diverge in their ability to dysregulate MHC I expression, it is not known what sequence determinants of HPV-E7 are responsible for this important functional difference. To investigate this, we analyzed the capability to affect MHC I of a set of chimeric E7 variants containing sequence elements from either high risk HPV16 or low risk HPV11. HPV16-E7, but not HPV11-E7, causes significant diminution of mRNA synthesis and surface presentation of MHC I, which depend on histone deacetylase activity. Our experiments demonstrate that the C-terminal region within the zinc finger domain of HPV-E7 is responsible for the contrasting effects of HPV11- and HPV16-E7 on MHC I. By using different loss- and gain-of-function mutants of HPV11- and HPV16-E7, we identify for the first time a residue variation at position 88 that is highly critical for HPV16-E7-mediated suppression of MHC I. Furthermore, our studies suggest that residues at position 78, 80, and 88 build a minimal functional unit within HPV16-E7 required for binding and histone deacetylase recruitment to the MHC I promoter. Taken together, our data provide new insights into how high risk HPV16-E7 dysregulates MHC I for immune evasion.

Human Leukocyte Antigens I and II Haplotypes Associated With Human Papillomavirus 16-Positive Invasive Cervical Cancer in Mexican Women

Infection with human papillomavirus (HPV), mainly HPV type 16, is the major etiologic factor associated with cervical cancer (CC), but HPV infection alone is not sufficient for progression of precursor lesions. Host genetic susceptibility may lead to abnormal immune response resulting from virus persistence. Several studies have suggested a possible association with specific human leukocyte antigen (HLA) class I and II alleles and CC, but results are not consistent. The association of genetic HLA class I (A and B) and HLA class II (DR*B1 and DQ*B1) haplotypes with HPV16-positive CC (n = 104) and base population controls (n = 104) was evaluated in this Mexican population study. Sequence-specific primer HLA genes were determined by polymerase chain reaction (PCR)-based methods in peripheral blood cell counts (PCR sequence-specific oligonucleotides). The cervical swabs of 208 women were tested for HPV16 by Hybrid Capture II. Allele and haplotype HLA frequencies, Hardy-Weinberg tests, and a haplotype homogeneity test were estimated using the Arlequin software v. 3.01. Odds ratio (OR) was calculated to compare cases and control women. Consistent associations across other studies in women with CC and infected by HPV16 were observed for HLA-DRB1*15 (OR, 3.9; 95% CI, 1.6-10.2) and the haplotype DRB1*15 DQB1*0602 (OR, 4.1; 95% CI, 1.4-12.7) compared with control women. The HLA-A2-B44-DR4-DQ*0302, HLA-A24-B35-DR16-DQ*0301, and HLA-A2-B40-DR4-DQ*0302 haplotypes showed a positive association with CC (OR, >1), whereas HLA-A2-B39-DR4-DQ*0302, HLA-A24-B35-DR4-DQ*0302, and HLA-A68-B40-DR4-DQ*0302 showed a negative association (OR, <1). These results support the hypothesis that some HLA class I and II haplotypes could be involved with susceptibility for developing CC.

Abbreviations:

Cervical Cancer-CC, confidence interval-CI, human leukocyte antigens-HLA, human papillomavirus-HPV, odds ratio-OR, polymerase chain reaction-PCR, relative risk-RR, relative light units-RLU, ribonucleic acid-RNA, sequence-sensitive oligonucleotide-SSO

The E6E7 oncoproteins of cutaneous human papillomavirus type 38 interfere with the interferon pathway

Non-melanoma skin cancer is the most frequent malignancy in Caucasian populations. Evidence suggests the involvement of cutaneous Human Papillomavirus (HPV) of the genus beta (beta) in this disease. The ability of E6 and E7 of mucosal HPV to promote cellular transformation and inhibit immune response-related pathways plays a key role in cervical carcinogenesis. beta HPV-38 E6 and E7 display transforming activities in in vitro and in vivo models, but their impact on immune surveillance is unknown. Here we show that HPV-38 E6 and E7 affect the IFN-induced up-regulation of MHC class I. Expression of the two viral proteins in HaCaT keratinocytes led to a decrease of MHC I levels. This down-regulation is associated with a reduction of expression of MHC I heavy chain, of the peptide chaperone TAP and of the STAT-1 downstream effector IRF-1. The down-regulation of these proteins is ultimately due to the inhibition of STAT-1 expression. Analysis of cells expressing either HPV-38 E6 or E7 suggests that these effects are primarily the result of E6 expression, although a contribution by E7 cannot be excluded. We conclude that HPV-38 encodes oncoproteins that potentially contribute to the evasion of host immune surveillance.

Predisposition to HPV16/18-related cervical cancer because of proline homozygosity at codon 72 of p53 among Indian women is influenced by HLA-B*07 and homozygosity of HLA-DQB1*03

This study was undertaken to examine whether predisposition to human papillomavirus (HPV)16/18-related cervical cancer (CaCx) because of p53 proline homozygosity (Pro72Pro) among Indian women was mediated singly or jointly with immunogenetic risk factors such as HLA-B*07 or homozygosity of HLA-DQB1*03. Molecular detection of all three genetic factors was performed by polymerase chain reaction-restriction fragment length polymorphism using DNA from (i) 114 CaCx samples (78 HPV16/18 positive) and (ii) 195 cytologically normal cervical scrapes (116 HPV-negative and 79 HPV16/18-positive samples). Multiple logistic regression analyses were performed to examine independent effects of the three factors and to determine age-adjusted odds ratio (OR) [95% confidence interval (CI)] and P-values. HLA-B*07 was observed to be significantly associated with HPV16/18 infection in asymptomatic controls (OR(age-adjusted) = 4.73; 95% CI: 1.55-14.45; P = 0.006) and CaCx (OR(age-adjusted) = 6.14; 95% CI: 2.15-17.53; P < 0.001) in this enhanced sample set of CaCx cases. There was a lack of association between HLA-B*07 and HLA-DQB1*03 in our study samples. The association of p53Pro72Pro with CaCx was non-significant in the absence of HLA-B*07 in HPV16/18-positive women. In this group, prevalence of p53Pro72Pro and HLA-B*07 together was significantly higher (7.0%) among CaCx cases (OR(age-adjusted) = 14.05; 95% CI: 1.11-177.30; P = 0.04), compared with controls (1.3%) lacking both factors. HLA-DQB1*03 homozygosity (OR(age-adjusted) = 4.75; 95% CI: 1.17-19.30; P = 0.03) or p53Pro72Pro (OR(age-adjusted) = 5.84; 95% CI: 1.18-28.99; P = 0.03) was found to be significantly associated with CaCx, each in the absence of the other in this group but not when present jointly in contrast to those lacking both factors (P = 0.214). Thus, modulation of p53Pro72Pro-mediated susceptibility to CaCx by immunogenetic factors could possibly be mediated through cross talk between HPV16/18-induced immune evasion and cell transformation.

Interleukin-10 gene (IL10) polymorphisms and human papillomavirus clearance among immunosuppressed adolescents

Persistent infection with high-risk human papillomavirus (HPV) is a major risk factor for cervical cancer, and HPV clearance seems to be under host genetic influence. This study evaluated associations between three single nucleotide polymorphisms in the IL10 promoter and clearance of low- or high-risk HPV infection in a cohort of 226 largely HIV-1-infected African-American adolescent females. Among immunosuppressed individuals (HIV-1 seropositive and CD4(+) </= 500), the GCC haplotype in the IL10 promoter was associated with reduced clearance of high-risk HPV16-like [relative hazard (RH), 0.46; 95% confidence interval (95% CI), 0.25-0.85; P = 0.01], HPV18-like (RH, 0.33; 95% CI, 0.16-0.67; P = 0.002), and any high-risk type (RH, 0.37; 95% CI, 0.20-0.68; P = 0.002) but not with low-risk HPV type (RH, 0.60; 95% CI, 0.29-1.25; P = 0.17). No associations were observed among immunocompetent individuals. The IL10 GCC haplotype has been associated with production of relatively high levels of interleukin (IL)-10, which could (a) inhibit cytokines such as IL-2, TNF-alpha, IL-4, IL-6, and IL-12 that are involved in the T(H)1-T(H)2 immunoregulation; (b) down-regulate expression of MHC class I and class II molecules; or (c) induce the transcription of early promoter of HPV, all potentially contributing to duration of HPV infection among immunosuppressed individuals. These results support the hypothesis that IL10 polymorphisms influence the clearance of infection with high-risk HPV types and warrant further studies of host genetic control of HPV pathogenesis and cervical cancer in the context of immunosuppression.

High-risk human papillomavirus E7 expression reduces cell-surface MHC class I molecules and increases susceptibility to natural killer cells

High-risk human papillomavirus (HPV) is a major causative agent of cervical cancer and the E6 and E7 genes encode the major HPV oncoproteins. The E7 protein from high-risk HPV types alters cell cycle progression and represses genes encoding components of the antigen-presentation pathway, suggesting a role for E7 in tumour immune evasion. We show that knockdown of E7 expression in HPV16- and HPV18-transformed cervical carcinoma cells by RNA interference increased expression of major histocompatibility complex (MHC) class I at the cell surface and reduced susceptibility of these cells to natural killer (NK) cells. Tetracycline-regulated induction of HPV16 E7 resulted in reduced expression of cell surface MHC class I molecules and increased NK cell killing. Our results suggest that, for HPV-associated malignancies, reduced MHC class I expression is the result of an active immune evasion strategy that has evolved to assist viral replication.

Immune concept of human papillomaviruses and related antigens in local cancer milieu of human cervical neoplasia

It is presently the right time for clarifying human papillomavirus (HPV)-associated cellular immunity and clinical implications before global HPV vaccination programs begin. Infection with oncogenic HPV associates with the progression of cervical neoplasia. Both cellular and humoral immune responses are essential for the clearance of HPV-associated cervical lesions. There is increasing evidence that the immune system plays a pivotal role in determining the outcome of HPV infection. Viruses and associated neoplastic cells are proposed to have evolved mechanisms to avoid immune attack. T-cell-mediated immune responses against oncogenic HPV are believed to play a central role in cervical carcinogenesis. The presence of HPV-specific cytotoxic T lymphocytes (CTL) in a majority of human cervical cancer patients provides an approach for further study of their functional role in modulating this malignancy. Tumor-infiltrating lymphocytes (TIL) develop as manifestations of the recognition and defense against malignant cells by the host immune system. Cancer cells may overcome immune surveillance, either by downregulating the proliferation of HPV-specific CTL, or altering the effector compositions of immune cells against HPV infections. TIL in the tumor microenvironment can be functionally inhibited and lose the ability of clonal proliferation as a result of depressed expression of IL-2Ralpha. The upregulation of inhibitory signaling relates to the modulation of the virus- and/or tumor-specific immune responses. Alteration of host genetic susceptibility may also lead to abnormal immune response as a general genomic instability resulting from virus persistence. Induction of HPV-specific immune responses is anticipated as an intimate point for the treatment of cervical neoplasia.

E7 properties of mucosal human papillomavirus types 26, 53 and 66 correlate with their intermediate risk for cervical cancer development

Epidemiological studies have demonstrated that 15 different mucosal human papillomavirus (HPV) types of the genus alpha of the HPV phylogetic tree are classified as high risk for cervical cancer development. Three additional HPV types of the same genus, HPV26, 53 and 66, are classified as probable high-risk types. In this study, we have characterized the biological properties of the E7 oncoproteins from these three HPV types. All of the corresponding E7 proteins were able to associate with retinoblastoma protein (pRb) and up-regulated the expression of several positive cell cycle regulators, i.e. CDK2, cyclin A and cylin E. However, HPV26 E7 appears to be more efficient than HPV53 and 66 E7 in up-regulating the transcription of cyclin A. Unlike E7 from the high-risk type HPV16 protein, HPV26, 53 and 66 did not efficiently promote pRb degradation. In addition, E7 from these viruses was able to promote proliferation of primary human keratinocytes and circumvent G1 arrest imposed by overexpression of p16(INK4a), but with less efficiency than the high-risk HPV16 E7. Together, our data show that in vitro properties of these E7 proteins correlate with the epidemiological classification of HPV26, 53 and 66 as HPV types with an intermediate risk for cervical cancer development.

TLR9 expression and function is abolished by the cervical cancer-associated human papillomavirus type 16

Cervical cancer development is linked to the persistent infection by high-risk mucosal human papillomaviruses (HPVs) types. The E6 and E7 major oncoproteins from this dsDNA virus play a key role in the deregulation of the cell cycle, apoptosis, and adaptive immune surveillance. In this study, we show for the first time that HPV type 16 (HPV16), the most carcinogenic type among the high-risk subgroup, interferes with innate immunity by affecting the expression of TLRs. Infection of human primary keratinocytes with HPV16 E6 and E7 recombinant retroviruses inhibits TLR9 transcription and hence functional loss of TLR9-regulated pathways. Similar findings were achieved in HPV16-positive cancer-derived cell lines and primary cervical cancers, demonstrating that this event occurs also in an in vivo context. Interestingly, E6 and E7 from the low-risk HPV type 6 are unable to down-regulate the TLR9 promoter. In addition, E6 and E7 from the high-risk HPV type 18, which are known to persist less competently in the host than HPV16, have reduced efficiency compared with HPV16 in inhibiting TLR9 transcription. Furthermore, a CpG motif derived from the HPV16 E6 DNA sequence activated TLR9, indicating this virus is able to initiate innate responses via the receptor it later down-regulates. This study reveals a novel mechanism used by HPV16 to suppress the host immune response by deregulating the TLR9 transcript, providing evidence that abolishing innate responses may be a crucial step involved in the carcinogenic events mediated by HPVs.

The E5 protein of BPV-4 interacts with the heavy chain of MHC class I and irreversibly retains the MHC complex in the Golgi apparatus

BPV-4 E5 inhibits transcription of the bovine MHC class I heavy chain (HC) gene, increases degradation of HC and downregulates surface expression of MHC class I by retaining the complex in the Golgi apparatus (GA). Here we report that transcription inhibition can be alleviated by interferon treatment and the degradation of HC can be reversed by treatment with inhibitors of proteasomes and lysosomes. However, the inhibition of transport of MHC class I to the cell surface is irreversible. We show that E5 is capable of physically interacting with HC. Together with the inhibition of the vacuolar ATPase (due to the interaction between E5 and 16k subunit c), the interaction between E5 and HC is likely to be responsible for retention of MHC class I in the GA. C-terminus deletion mutants of E5 are incapable of either downregulating surface MHC class I or interacting with HC, establishing that the C-terminus domain of E5 is important in the inhibition of MHC class I.

Immunohistochemical analysis of CD4+ and CD8+ T-cell subsets in high risk human papillomavirus-associated pre-malignant and malignant lesions of the uterine cervix

OBJECTIVES

Humoral and cellular immune responses are likely to play a key role for the clearance or persistence and progression of high risk (HR) HPV-associated cervical lesions. Although there are many studies describing the systemic T-cell responses to HPV16 and 18 proteins, few data are available regarding the cellular mucosal immune responses. We used immunohistochemistry to characterize populations of T-immune cells (CD4+, CD8+, CD45RO+) in HR-HPV-infected precancerous and cancerous lesions of the uterine cervix.

METHODS

Four biopsies from normal cervix, 9 CIN1 which have regressed (rCIN), 5 CIN1 which have progressed (pCIN) to high grade lesions, 13 CIN3 and 11 invasive carcinomas were included. All dysplasias and carcinomas were HR-HPV-positive and low-risk-HPV-negative. They were stained with monoclonal antibodies specific for CD4, CD8 and CD45RO and examined by microscopy.

STATISTICAL ANALYSIS

The Kruskal-Wallis test and the Siegel's and Castelan's method were used. RESULTS.: CD4+ cells predominated in regressing CIN1 both within the stroma and the epithelium with the highest CD4+/CD8+ ratio compared with pCIN1, CIN3 and invasive carcinoma. At the exception of CD45RO+ cells, T cells were detected with similar frequencies in both pCIN1 and CIN3. However, in 7 out of 10 CIN3, CD4+ and CD8+ cells were visible as organized lymphoid follicle structure. The CD8+ and CD45RO+ cells far exceeded the CD4+ cells in invasive cancers.

CONCLUSIONS

Density and distribution of immune T cells depend on the malignant potential of HR-HPV lesions. These results suggest that the studied lymphocyte subsets have an important role to fulfil during the natural history of HR-HPV-associated lesions.

Association of tumor necrosis factor a-2 and a-8 microsatellite alleles with human papillomavirus and squamous intraepithelial lesions among women in Brazil

Infection with oncogenic human papillomavirus (HPV) is considered to be the major risk factor for cervical cancer. Tumor necrosis factor (TNF) is a pluripotent cytokine that plays an important role in inhibiting the action of microbial agents, and TNF microsatellite polymorphisms have been associated with several diseases, including cancer and viral infections. This study analyzed the associations between TNFa to -e microsatellite polymorphisms and the severity of squamous intraepithelial lesions (SIL), according to the presence of the oncogenic HPV16 and HPV18 types. Samples from 146 HPV-positive women with low-grade SIL (LSIL) and high-grade SIL (HSIL) and samples from 101 healthy women were studied. TNF microsatellite polymorphism typing and HPV detection and typing were performed using PCR-amplified DNA hybridized with sequence-specific primers. Data were analyzed by Fisher's exact test using the GENEPOP software. Significant associations were observed between LSIL and the TNFa-8 allele (4/166; P = 0.04), as well as between TNFa-2 with HPV18 only (16/44; P = 0.002) and TNFa-2 with HPV18 coinfection with HPV16 (16/44; P = 0.001). Patients exhibiting the TNFa-2 allele and harboring HPV18, in the presence or absence of coinfection with HPV16, had an increased risk of HSIL occurrence (13/38; P = 0.04; 5/10; P = 0.04) compared to patients with other HPV types. These results suggest that the TNFa-8 allele is associated with increased susceptibility to the occurrence of LSIL and that despite the presence of a high TNF-alpha production allele, the ability of HPV18 to resist the inhibitory effects of TNF-alpha may contribute to the occurrence of infection and consequently to HSIL in women with cervical HPV18 infection.

E5 protein of human papillomavirus type 16 selectively downregulates surface HLA class I

Papillomaviruses have evolved mechanisms that result in escape from host immune surveillance. The E5 protein is expressed early in papillomavirus infection in the deep layers of the infected epithelium. It is localized to the Golgi apparatus (GA) and endoplasmic reticulum. The E5 protein of bovine papillomavirus (BPV) impairs the synthesis and stability of major histocompatibility (MHC) class I complexes and prevents their transport to the cell surface due to retention in the GA. Here we show that human papillomavirus type 16 (HPV-16) E5 also causes the retention of MHC (HLA) class I complexes in the GA and impedes their transport to the cell surface, which is rescued by treatment with interferon. Unlike BPV E5, HPV-16 E5 does not affect the synthesis of HLA class I heavy chains or the expression of the transporter associated with antigen processing TAP. These results show that downregulation of surface MHC class I molecules is common to both BPV and HPV E5 proteins. Moreover, we determined that HPV-16 E5 downregulates surface expression of HLA-A and HLA-B, which present viral peptides to MHC class I-restricted cytotoxic T lymphocytes (CTLs), but not the natural killer (NK) cell inhibitory ligands HLA-C and HLA-E. Selective downregulation of cell surface HLA class I molecules may allow the virus to establish infection by avoiding immune clearance of virus-infected cells by both CTLs and NK cells.