Loss of epidermal Langerhans cells occurs in human papillomavirus alpha, gamma, and mu but not beta genus infections

The HPV viral regulatory mechanism of TLRs and the related treatments for HPV-associated cancers

Infection with human papillomavirus (HPV) typically leads to cervical cancer, skin related cancers and many other tumors. HPV is mainly responsible for evading immune tumor monitoring in HPV related cancers. Toll like receptors (TLRs) are particular pattern recognition molecules. When the body is facing immune danger, it can lead to innate and direct adaptive immunity. TLR plays an important role in initiating antiviral immune responses. HPV can affect the expression level of TLR and interfere with TLR related signaling pathways, resulting in sustained viral infection and even carcinogenesis. This paper introduces the HPV virus and HPV related cancers. We discussed the present comprehension of TLR, its expression and signaling, as well as its role in HPV infection. We also provided a detailed introduction to immunotherapy methods for HPV related diseases based on TLR agonists. This will provide insights into methods that support the therapeutic method of HPV related conditions with TLR agonists.

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.

Decreased CD1a + and CD83 + cells in tonsillar squamous cell carcinoma regardless of HPV status

Dendritic cells (DCs) are specialized antigen-presenting cells that play a critical role in the immune response against human papillomavirus (HPV) infection, and represent a therapeutic target in cancer.

Dermatologists' Impressions of Spontaneously Regressing Verruca Plana Histopathology

ABSTRACT

Verruca plana in its regressing phase exhibits clinical and histological features distinct from classic verruca plana, but the ways in which these features should inform treatment plans are still under investigation. We conducted a retrospective single-center analysis of 25 patients with features of classic verruca plana, or plane warts, who exhibited self-remission within 4 weeks of skin biopsy. Measures included lesion sites, clinical findings preceding regression, and histological analysis. Histological analysis involved review by 2 dermatologists followed by impressions given by 4 board-certified dermatologists who were blinded to the clinical characteristics of the patients. Histopathological findings of regressing plane warts showed superficial perivascular infiltration (96%), spongiosis and exocytosis (84%), basal vacuolization (64%), parakeratosis (64%), apoptotic keratinocytes (60%), and lichenoid infiltration (44%). These findings were more compatible with the histological patterns of pityriasis lichenoides, lichen planus, and spongiotic eczema, rather than classic verruca plana. This suggests that regressing verruca plana may be included in the differential diagnosis of lesions exhibiting a lichenoid or spongiotic reaction, and observation may be a favorable treatment plan in these patients.

The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis

Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy-as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7-the not-so-good, the bad and the ugly-and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.

Type 2 human papillomavirus E7 attenuates E-cadherin expression in human keratinocytes

Human papillomaviruses (HPVs) are known to utilize the down-regulation of epithelial (E)-cadherin, a major component of adherens junctions of keratinocytes, to evade host immune surveillance in high-risk group. However, the effects of HPV on the function of E-cadherin in low-risk groups remain unknown. We investigated whether type 2 HPV (HPV-2) E7 could induce alterations in E-cadherin expression in transiently transfected keratinocytes and cell lines expressing HPV-2 E7. To examine the expression pattern of E-cadherin in cutaneous warts and normal skin samples, immunohistochemical analysis was performed. Quantitative real-time polymerase chain reactions, luciferase assays, western blot, immunocytochemistry, and electron microscopy were used to evaluate the mRNA and protein expression levels of E-cadherin in normal human epidermal keratinocytes transfected with HPV-2 E7 plasmid DNA or E7-specific siRNA and in E7-expressing cell lines. E-cadherin expression levels in HPV-2 positive cutaneous warts were significantly decreased compared to those in normal skin (p < 0.05). Similarly, the mRNA and protein expression levels of E-cadherin in E7 transiently transfected cells were significantly decreased compared to those in empty vector-transfected cells. The decreases were restored by transfection with E7-specific siRNA (p < 0.05). Likewise, cell lines expressing E7 showed a decreased expression of E-cadherin. When the cells were cultured in low attachment plates, cell-to-cell aggregation was inhibited. Taken together, our data suggest that HPV-2 E7, the causative agent of cutaneous warts, could mediate the transcriptional repression of E-cadherin.

Pathogenic Role of Immune Evasion and Integration of Human Papillomavirus in Oropharyngeal Cancer

The incidence of oropharyngeal cancer (OPC) is increasing remarkably among all head and neck cancers, mainly due to its association with the human papillomavirus (HPV). Most HPVs are eliminated by the host’s immune system; however, because HPV has developed an effective immune evasion mechanism to complete its replication cycle, a small number of HPVs are not eliminated, leading to persistent infection. Moreover, during the oncogenic process, the extrachromosomal HPV genome often becomes integrated into the host genome. Integration involves the induction and high expression of E6 and E7, leading to cell cycle activation and increased genomic instability in the host. Therefore, integration is an important event in oncogenesis, although the associated mechanism remains unclear, especially in HPV-OPC. In this review, we summarize the current knowledge on HPV-mediated carcinogenesis, with special emphasis on immune evasion and integration mechanisms, which are crucial for oncogenesis.

Epstein-Barr virus may contribute to the pathogenesis of adult-onset recurrent respiratory papillomatosis: A preliminary study

OBJECTIVE

Human papillomavirus (HPV) causes adult-onset recurrent respiratory papillomatosis (AORRP), but AORPP prevalence is much lower than HPV prevalence. Thus, HPV infection is necessary, but not sufficient, to cause AORRP and other factors likely contribute to its pathogenesis. The present study aimed to investigate whether co-infection with herpetic viruses may contribute to the pathogenesis of AORRP.

DESIGN

Prospective case-control study conducted from January 2018 to November 2019.

SETTINGS

Tertiary referral centre.

PARTICIPANTS

Eighteen consecutive patients with AORRP and 18 adults with healthy laryngeal mucosa (control group) undergoing surgery.

MAIN OUTCOME MEASURES

Cytomegalovirus, Epstein-Barr virus (EBV), herpes simplex viruses 1 and 2, human herpesvirus 6, varicella zoster virus and HPV (including genotyping) were detected in biopsies of papilloma or healthy mucosa using real-time polymerase chain reaction and reverse line blot. Dysplasia and Ki67 levels were determined in papilloma specimens.

RESULTS

EBV was present in 6 (33.3%) AORRP patients and no control patients (P = .019). Presence was not dependent on tobacco exposure (P = .413) or HPV genotype or concentration (P > .999). EBV presence was strongly related to increased cell proliferation (P = .005) and number of previous surgeries (P = .039), but not dysplasia (P > .999). Human herpesvirus 6 was found in 3 (16.7%) AORRP biopsies, with one false positive. No other herpetic virus was found.

CONCLUSIONS

Unlike other herpetic viruses, EBV seems to interact with HPV, enhancing cell proliferation and contributing to the pathogenesis and progression of AORRP. Further research is required to elucidate specific interactions and their role in the pathogenesis of AORRP.

Immunology of HPV-mediated cervical cancer: current understanding

Human papilloma virus (HPV) has emerged as a primary cause of cervical cancer worldwide. HPV is a relatively small (55 nm in diameter) and non-enveloped virus containing approximately 8 kb long double stranded circular DNA genome. To date, 228 genotypes of HPV have been identified. Although all HPV infections do not lead to the development of malignancy of cervix, only persistent infection of high-risk types of HPV (mainly with HPV16 and HPV18) results in the disease. In addition, the immunity of the patients also acts as a key determinant in the carcinogenesis. Since, no HPV type specific medication is available for the patient suffering with cervical cancer, hence, a deep understanding of the disease etiology may be vital for developing an effective strategy for its prevention and management. From the immunological perspectives, the entire mechanisms of disease progression still remain unclear despite continuous efforts. In the present review, the recent developments in immunology of HPV-mediated cervix carcinoma were discussed. At the end, the prevention of disease using HPV type specific recombinant vaccines was also highlighted.

Human genetic dissection of papillomavirus-driven diseases: new insight into their pathogenesis

Human papillomaviruses (HPVs) infect mucosal or cutaneous stratified epithelia. There are 5 genera and more than 200 types of HPV, each with a specific tropism and virulence. HPV infections are typically asymptomatic or result in benign tumors, which may be disseminated or persistent in rare cases, but a few oncogenic HPVs can cause cancers. This review deals with the human genetic and immunological basis of interindividual clinical variability in the course of HPV infections of the skin and mucosae. Typical epidermodysplasia verruciformis (EV) is characterized by β-HPV-driven flat wart-like and pityriasis-like cutaneous lesions and non-melanoma skin cancers in patients with inborn errors of EVER1-EVER2-CIB1-dependent skin-intrinsic immunity. Atypical EV is associated with other infectious diseases in patients with inborn errors of T cells. Severe cutaneous or anogenital warts, including anogenital cancers, are also driven by certain α-, γ-, μ or ν-HPVs in patients with inborn errors of T lymphocytes and antigen-presenting cells. The genetic basis of HPV diseases at other mucosal sites, such as oral multifocal epithelial hyperplasia or juvenile recurrent respiratory papillomatosis (JRRP), remains poorly understood. The human genetic dissection of HPV-driven lesions will clarify the molecular and cellular basis of protective immunity to HPVs, and should lead to novel diagnostic, preventive, and curative approaches in patients.

E6‑regulated overproduction of prostaglandin E2 may inhibit migration of dendritic cells in human papillomavirus 16‑positive cervical lesions

Continuous human papillomavirus (HPV) infection is a critical cause of cervical lesions; however, the specific mechanism is currently not clear. E6 is one of the most important oncoproteins associated with HPV, which regulates synthases in the production of prostaglandin E2 (PGE₂). Notably, PGE₂ has been reported to be upregulated in cervical lesions. An insufficient number of mature dendritic cells (DCs), which is unable to cause an effective immune response, is an important cause of cervical lesions. Therefore, this study explored the possible causes of HPV16-positive cervical lesions by identifying the relationship between E6, PGE₂ and DCs. Firstly, the distribution and status of DCs in clinical biopsy specimens and animal models were analyzed with immuno-histochemistry and flow cytometry, which demonstrated that the migratory ability of DCs was inhibited in HPV16-positive cervical lesions. Furthermore, using immunohistochemistry, western blotting and ELISA, it was revealed that as the degree of cervical lesions increased, the expression of PGE₂ and its synthases increased. Subsequently, as determined using Transwell and 3D migration assays, it was revealed that a high concentration of PGE₂ inhibited the migration of DCs, which may explain the phenomenon observed in cervical lesions. Notably, E6 was identified to regulate PGE₂ expression. The in vivo experiments indicated that E6 may increase the expression levels of PGE₂ in cervical lesions, which could eventually induce inhibition of the migration of DCs. In conclusion, the present study suggested that E6 regulated overproduction of PGE₂, which may induce inhibition of DC migration in HPV16-positive cervical lesions.

Condylomata Acuminata (Anogenital Warts) Contain Accumulations of HIV-1 Target Cells That May Provide Portals for HIV Transmission

Background

Condylomata acuminata (anogenital warts [AGWs]) are prevalent in human immunodeficiency virus (HIV)-infected individuals and sexually active populations at risk for HIV acquisition and have been associated with HIV transmission. We compared AGW specimens to control tissue specimens for abundance, types, and location of HIV target cells and for susceptibility to HIV infection in vitro, to provide biologic evidence that AGWs facilitate HIV transmission.

Methods

We used immunohistologic staining to identify HIV target cells in AGW and control specimens. We also inoculated HIV in vitro into AGW and control specimens from HIV-negative men and assessed infection by means of TZM-bl and p24 assays.

Results

CD1a+ dendritic cells, CD4+ T cells, and macrophages were significantly more abundant in the epidermis of AGW specimens than control specimens. These HIV target cells also often appeared in large focal accumulations in the dermis of AGW specimens. Two of 8 AGW specimens versus 0 of 8 control specimens showed robust infection with HIV in vitro.

Conclusions

Compared with normal skin, AGWs contain significantly higher concentrations of HIV target cells that may be susceptible to HIV infection. Condylomata may thus promote HIV transmission, especially in the setting of typical lesion vascularity and friability. Prevention or treatment of AGWs may decrease the sexual transmission of HIV.

Microparticles produced by human papillomavirus type 16 E7-expressing cells impair antigen presenting cell function and the cytotoxic T cell response

High-risk, cancer-causing human papillomaviruses (HPV) cause infections of the epidermis that may progress to cancer, including cervical cancer. Viral persistence, contributed to by viral evasion of the host immune response, is associated with the likelihood of cancer developing. Langerhans cells (LCs) are the only professional antigen presenting cells located in the epidermis, therefore may influence the antiviral immune response. Microparticles, or microvesicles, are small membrane particles shed by cells that can exert effects on other cells at both a local and systemic level. We found increased numbers of microparticles were shed from human or mouse keratinocytes expressing the HPV16 E7 oncoprotein, compared with control keratinocytes. Co-culture of LCs with microparticles from E7-expressing cells suppressed the cytotoxic T cell response. We attributed this, at least in part, to the reduction in surface of CD40 and intracellular pro-inflammatory cytokine IL-12 p40 subunit that we measured in the LCs. The evidence provided here shows that co-culture of E7-microparticles with LCs inhibits antigen-specific cytotoxicity. This is an important finding, suggesting that microparticles from HPV-infected cells could suppress the T cell response by regulating LCs, potentially contributing to persistence of HPV infection and cancer.

Modulation of antigen presenting cell functions during chronic HPV infection

High-risk human papillomaviruses (HR-HPV) infect basal keratinocytes, where in some individuals they evade host immune responses and persist. Persistent HR-HPV infection of the cervix causes precancerous neoplasia that can eventuate in cervical cancer. Dendritic cells (DCs) are efficient in priming/cross-priming antigen-specific T cells and generating antiviral and antitumor cytotoxic CD8+ T cells. However, HR-HPV have adopted various immunosuppressive strategies, with modulation of DC function crucial to escape from the host adaptive immune response. HPV E6 and E7 oncoproteins alter recruitment and localization of epidermal DCs, while soluble regulatory factors derived from HPV-induced hyperplastic epithelium change DC development and influence initiation of specific cellular immune responses. This review focuses on current evidence for HR-HPV manipulation of antigen presentation in dendritic cells and escape from host immunity.

Clinical implications of the interaction between HPV and HIV infections

HIV-related immunodeficiency has complex effects on female genital HPV, which include increased risks of infection, multiple types, persistence, reactivation and the risk to develop pre-invasive and invasive disease. Reconstitution of immunity with anti-viral drugs improves cellular immunity, but the risk of HPV-related malignancy remains higher than background incidences and presents at younger ages. Early initiation of antiretroviral therapy (ART) allows improved retention of immune memory through existing antibodies and T-cell clones and improves long-term outcomes. Suggestions of a higher risk to contract HIV if there is existing genital HPV infection are supported and explained by pathophysiological cervical changes, including inflammation. HIV-HPV interactions should influence public health decisions towards prioritising large-scale prepubertal HPV-vaccine roll-out, secondary cervical cancer prevention and early detection programmes for HIV-infected women and early initiation of ART. This chapter will also focus on special considerations for the management of women with co-infection with these two viruses and genital HPV-related diseases.

Absence of γ-Chain in Keratinocytes Alters Chemokine Secretion, Resulting in Reduced Immune Cell Recruitment

Loss-of-function mutations in the common gamma (γc) chain cytokine receptor subunit give rise to severe combined immunodeficiency characterized by lack of T and natural killer cells and infant death from infection. Hematopoietic stem cell transplantation or gene therapy offer a cure, but despite successful replacement of lymphoid immune lineages, a long-term risk of severe cutaneous human papilloma virus infections persists, possibly related to persistent γc-deficiency in other cell types. Here we show that keratinocytes, the only cell type directly infected by human papilloma virus, express functional γc and its co-receptors. After stimulation with the γc-ligand IL-15, γc-deficient keratinocytes show significantly impaired secretion of specific chemokines including CXCL1, CXCL8, and CCL20, resulting in reduced chemotaxis of dendritic cells and CD4⁺ T cells. Furthermore, γc-deficient keratinocytes also exhibit defective induction of T-cell chemotaxis in a model of stable human papilloma virus-18 infection. These findings suggest that persistent γc-deficiency in keratinocytes alters immune cell recruitment to the skin, which may contribute to the development and persistence of warts in this condition and would require different treatment approaches.

Suppression of the CD8 T cell response by human papillomavirus type 16 E7 occurs in Langerhans cell-depleted mice

Human papillomavirus (HPV) is an epitheliotropic virus that is the primary causal agent for cervical cancer. Langerhans cells (LC) are skin antigen presenting cells that are reduced in number in HPV-infected skin. The aim of this study was to understand the immune-modulatory effects of HPV16 E7 on LC and on the CD8 T cell response to a skin-expressed antigen. To test this, HPV16 E7 was expressed in mouse skin keratinocytes with the model antigen ovalbumin (Ova). Similar to what is observed in HPV-infected human skin, LC numbers were significantly reduced in E7-expressing mouse skin. This shows that expression of the E7 protein alone is sufficient to mediate LC depletion. Expression of E7 with Ova in keratinocytes strongly suppressed the Ova-specific CD8⁺ T cell response in the skin draining lymph node. When tested in LC-ablated mice, the CD8 T cell response to skin-expressed Ova in control mice was not affected, nor was the T cell response to Ova restored in E7-expressing skin. These data indicate a role for E7 in regulation of LC homeostasis in the skin and in suppression of antigen specific CD8 T cell expansion, but suggest that these two effects occur independent of each other.

Moving forward with human papillomavirus immunotherapies

Persistent human papillomavirus (HPV) is the primary etiologic agent of cervical cancer and causes a significant number of vulvar, penile, anal and oropharyngeal cancers. The development of highly effective HPV therapeutic vaccines is a reasonable goal given the recent advances in basic and applied immunology. A number of vaccine strategies designed to induce systemic T cell responses have been tested in clinical trials against high grade cervical or vulvar high grade neoplasia and cancers, but with limited success. In line with the emerging trend to focus more on the epithelial context of HPV infection and premalignant disease, it might be advantageous to develop vaccination strategies that promote trafficking of HPV-specific T cells into lesions and overcome the local immunosuppressive environment. The development of more biologically relevant animal models would improve the preclinical evaluation of therapeutic vaccine candidates. Finally, persistent infection and low grade lesions may prove to be easier targets for therapeutic vaccines, and these vaccines would likely be commercially viable in high income countries and valuable components in screen and treat programs in low resource settings.

Langerhans cells from women with cervical precancerous lesions become functionally responsive against human papillomavirus after activation with stabilized Poly-I:C

Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to persistent infection and development of cervical intraepithelial neoplasia (CIN). Women with HPV-induced high-grade CIN2/3 have not mounted an effective immune response against HPV, yet it is unknown if LC-mediated T cell activation from such women is functionally impaired against HPV. We investigated the functional activation of in vitro generated LC and their ability to induce HPV16-specific T cells from CIN2/3 patients after exposure to HPV16 followed by treatment with stabilized Poly-I:C (s-Poly-I:C). LC from patients exposed to HPV16 demonstrated a lack of costimulatory molecule expression, inflammatory cytokine secretion, and chemokine-directed migration. Conversely, s-Poly-I:C caused significant phenotypic and functional activation of HPV16-exposed LC, which resulted in de novo generation of HPV16-specific CD8(+) T cells. Our results highlight that LC of women with a history of persistent HPV infection can present HPV antigens and are capable of inducing an adaptive T cell immune response when given the proper stimulus, suggesting that s-Poly-I:C compounds may be attractive immunomodulators for LC-mediated clearance of persistent HPV infection.

Suppression of Langerhans cell activation is conserved amongst human papillomavirus α and β genotypes, but not a µ genotype

Human papillomavirus (HPV) has evolved mechanisms that allow it to evade the human immune system. Studies have shown HPV-mediated suppression of activation of Langerhans cells (LC) is a key mechanism through which HPV16 evades initial immune surveillance. However, it has not been established whether high- and low-risk mucosal and cutaneous HPV genotypes share a common mechanism of immune suppression. Here, we demonstrate that LC exposed to capsids of HPV types 18, 31, 45, 11, (alpha-papillomaviruses) and HPV5 (beta-papillomavirus) similarly suppress LC activation, including lack of costimulatory molecule expression, lack of cytokine and chemokine secretion, lack of migration, and deregulated cellular signaling. In contrast, HPV1 (mu-papillomavirus) induced costimulatory molecule and cytokine upregulation, but LC migration and cellular signaling was suppressed. These results suggest that alpha and beta HPV genotypes, and partially a mu genotype, share a conserved mechanism of immune escape that enables these viruses to remain undetected in the absence of other inflammatory events.

Role of innate immunity against human papillomavirus (HPV) infections and effect of adjuvants in promoting specific immune response

During the early stages of human papillomavirus (HPV) infections, the innate immune system creates a pro-inflammatory microenvironment by recruiting innate immune cells to eliminate the infected cells, initiating an effective acquired immune response. However, HPV exhibits a wide range of strategies for evading immune-surveillance, generating an anti-inflammatory microenvironment. The administration of new adjuvants, such as TLR (Toll-like receptors) agonists and alpha-galactosylceramide, has been demonstrated to reverse the anti-inflammatory microenvironment by down-regulating a number of adhesion molecules and chemo-attractants and activating keratinocytes, dendritic (DC), Langerhans (LC), natural killer (NK) or natural killer T (NKT) cells; thus, promoting a strong specific cytotoxic T cell response. Therefore, these adjuvants show promise for the treatment of HPV generated lesions and may be useful to elucidate the unknown roles of immune cells in the natural history of HPV infection. This review focuses on HPV immune evasion mechanisms and on the proposed response of the innate immune system, suggesting a role for the surrounding pro-inflammatory microenvironment and the NK and NKT cells in the clearance of HPV infections.

Association of genital human papillomavirus infection with HIV acquisition: a systematic review and meta-analysis

Objectives

To conduct a systematic review and a meta-analysis of epidemiological studies investigating the association of genital human papillomavirus (HPV) infection and HIV acquisition.

Design

Systematic review and meta-analysis.

Data Sources

Scientific databases and conference abstracts were systematically searched to identify all relevant studies published up to 31 January 2012. Search terms included ‘HIV’, ‘HPV’, ‘human papillomavirus’ and ‘papillomaviridae’ as keywords or text, in the title or abstract.

Methods

To be eligible for inclusion, a study had to be conducted among humans, report data on HIV incidence, and assess genital HPV infection. Summary ORs and 95% CIs were estimated from the extracted data using random-effect meta-analysis. Subgroup analyses were conducted for high-risk (HR) and low-risk (LR) HPV oncogenic risk groups. Between-study heterogeneity and publication bias were assessed.

Results

Of 2601 identified abstracts, six observational studies, comprising 6567 participants were retained for the systematic review and the meta-analysis. HIV acquisition was significantly associated with HPV infection (summary OR=1.96; 95% CI 1.55 to 2.49). HIV incident infection was significantly associated with HR-HPV in five of six studies and with LR-HPV in two out of five. The association was significant for HR-HPV (summary OR=1.92; 95% CI 1.49 to 2.46) and borderline for LR-HPV. No between-study heterogeneity was detected. There was a borderline indication of publication bias.

Conclusions

Further research is needed to elucidate the biological mechanisms involved, and assess the effect of HPV vaccination on HIV acquisition, using vaccines with broad coverage of HPV genotypes. Such research could have important public health implications for HIV prevention.

An enhanced heterologous virus-like particle for human papillomavirus type 16 tumour immunotherapy

Cervical cancer is caused by high-risk, cancer-causing human papillomaviruses (HPV) and is the second highest cause of cancer deaths in women globally. The majority of cervical cancers express well-characterized HPV oncogenes, which are potential targets for immunotherapeutic vaccination. Here we develop a rabbit haemorrhagic disease virus (RHDV) virus-like particle (VLP)-based vaccine designed for immunotherapy against HPV16 positive tumours. An RHDV-VLP, modified to contain the universal helper T cell epitope PADRE and decorated with an MHC I-restricted peptide (aa 48–57) from the HPV16 E6, was tested for its immunotherapeutic efficacy against the TC-1 HPV16 E6 and E7-expressing tumour in mice. The E6-RHDV-VLP-PADRE was administered therapeutically for the treatment of a pre-existing TC-1 tumour and was delivered with antibodies either to deplete regulatory T cells (anti-CD25) or to block T cell suppression mediated through CTLA-4. As a result, the tumour burden was reduced by around 50% and the median survival time of mice to the humane endpoint was almost doubled the compared to controls. The incorporation of PADRE into the RHDV-VLP was necessary for an E6-specific enhancement of the anti-tumour response and the co-administration of the immune modifying antibodies contributed to the overall efficacy of the immunotherapy. The E6-RHDV-VLP-PADRE shows immunotherapeutic efficacy, prolonging survival for HPV tumour-bearing mice. This was enhanced by the systemic administration of immune-modifying antibodies that are commercially available for use in humans. There is potential to further modify these particles for even greater efficacy in the path to development of an immunotherapeutic treatment for HPV precancerous and cancer stages.

Langerhans cell density in cervical intraepithelial neoplasia associated with human papillomavirus infection in HIV-infected and HIV-noninfected Brazilian women

OBJECTIVE

Local immunity plays an important role in the cervical defense mechanisms that prevent the development of cervical intraepithelial neoplasia. The objective of this study was to determine the involvement of local immunity by evaluating Langerhans cell (LC) density in cervical biopsies of human immunodeficiency virus (HIV)-positive and HIV-negative women.

MATERIALS AND METHODS

A cross-sectional study was developed by including HIV-positive and HIV-negative women. All patients presented human papillomavirus DNA from the uterine cervix, which was detected by polymerase chain reaction or hybrid capture II. Cervical biopsies were assessed for LC density and cervical intraepithelial neoplasia. Langerhans cells were identified by immunohistochemistry using anti-CD1a and anti-S100 antibodies. Associations among cervical LC density, the type of cervical lesion, CD4 lymphocyte count, and HIV viral load were analyzed using logistic regression (SPSS, version 12.0).

RESULTS

Seventy-seven women (40 seropositive and 37 seronegative) were enrolled. The mean ± SD LC density identified with the anti-CD1a antibody was 0.80 ± 0.7 cells versus 2.6 ± 1.6 cells (P < 0.0001), whereas the mean ± SD LC density identified by the anti-S100 antibody was 1.3 ± 1.0 cells versus 3.6 ± 1.7 cells (P < 0.0001) among the HIV-positive and HIV-negative women, respectively. There were no associations between LC density and HIV viral load, CD4 lymphocyte count, or human papillomavirus genotype (P > 0.05). In a logistic regression model, HIV infection was the only factor independently associated with a decrease in LC density.

CONCLUSIONS

Human immunodeficiency virus infection was found to be an independent factor that explains the decrease in local immunity in the uterine cervix, which could allow the development of cervical lesions. This effect was not associated with CD4 lymphocyte count or HIV viral load.

The immune response to papillomavirus during infection persistence and regression

Human papillomavirus (HPV) infections cause a significant global health burden, predominantly due to HPV-associated cancers. HPV infects only the epidermal cells of cutaneous and mucosal skin, without penetration into the dermal tissues. Infections may persist for months or years, contributed by an array of viral immune evasion mechanisms. However in the majority of cases immunity-based regression of HPV lesions does eventually occur. The role of the innate immune response to HPV in persistence and regression of HPV infection is not well understood. Although an initial inflammatory infiltrate may contribute to disease regression, sustained inflammation at the HPV-induced lesions, characterized by macrophage and neutrophil infiltration, has been observed in persistence. Pathogen-associated molecular patterns (PAMPs) are important in innate recognition. The double stranded DNA and an L1 and L2 capsid components of the HPV virion are potential PAMPs that can trigger signaling through cellular pattern recognition receptors, including toll-like receptors (TLR). TLR expression is increased in regressing HPV disease but is reduced in persistent lesions, suggesting a role for TLR in HPV regression. With regard to the adaptive immune response, a key indicator of regression in humans is infiltration of the lesion with both CD4 and CD8 T cells. In individuals with persistent lesions, CD8 T cell and immune suppressive regulatory T cells (Tregs) infiltrate the infection site. There is no association between persistence or regression and the presence of serum antibodies to the viral capsid antigens of HPV. There is still much to be learned about the immunological events that trigger regression of HPV disease. Understanding the viral and host factors that influence persistence and regression is important for the development of better immunotherapeutic treatments for HPV-associated disease.

Transcriptional repression of E-cadherin by human papillomavirus type 16 E6

There is increasing evidence supporting DNA virus regulation of the cell adhesion and tumour suppressor protein, E-cadherin. We previously reported that loss of E-cadherin in human papillomavirus (HPV) type 16-infected epidermis is contributed to by the major viral proto-oncogene E6 and is associated with reduced Langerhans cells density, potentially regulating the immune response. The focus of this study is determining how the HPV16 E6 protein mediates E-cadherin repression. We found that the E-cadherin promoter is repressed in cells expressing E6, resulting in fewer E-cadherin transcripts. On exploring the mechanism for this, repression by increased histone deacetylase activity or by increased binding of trans-repressors to the E-cadherin promoter Epal element was discounted. In contrast, DNA methyltransferase (DNMT) activity was increased in E6 expressing cells. Upon inhibiting DNMT activity using 5-Aza-2'-deoxycytidine, E-cadherin transcription was restored in the presence of HPV16 E6. The E-cadherin promoter was not directly methylated, however a mutational analysis showed general promoter repression and reduced binding of the transactivators Sp1 and AML1 and the repressor Slug. Expression of E7 with E6 resulted in a further reduction in surface E-cadherin levels. This is the first report of HPV16 E6-mediated transcriptional repression of this adhesion molecule and tumour suppressor protein.

New Approaches to Immunotherapy for HPV Associated Cancers

Cervical cancer is the second most common cancer of women worldwide and is the first cancer shown to be entirely induced by a virus, the human papillomavirus (HPV, major oncogenic genotypes HPV-16 and -18). Two recently developed prophylactic cervical cancer vaccines, using virus-like particles (VLP) technology, have the potential to prevent a large proportion of cervical cancer associated with HPV infection and to ensure long-term protection. However, prophylactic HPV vaccines do not have therapeutic effects against pre-existing HPV infections and do not prevent their progression to HPV-associated malignancy. In animal models, therapeutic vaccines for persisting HPV infection can eliminate transplantable tumors expressing HPV antigens, but are of limited efficacy in inducing rejection of skin grafts expressing the same antigens. In humans, clinical trials have reported successful immunotherapy of HPV lesions, providing hope and further interest. This review discusses possible new approaches to immunotherapy for HPV associated cancer, based on recent advances in our knowledge of the immunobiology of HPV infection, of epithelial immunology and of immunoregulation, with a brief overview on previous and current HPV vaccine clinical trials.

Genital human Papillomavirus infection in patients with autoimmune inflammatory diseases

Treatment advances achieved over the last few years have radically changed the management of patients with autoimmune inflammatory diseases requiring conventional or biological immunosuppressive therapy. These diseases and the drugs used to treat them increase the rate of infections, including genital infections due to the human Papillomavirus (HPV). Genital HPV infections have been extensively studied in organ transplant recipients, HIV-infected patients, and patients with congenital immune deficiencies. Although genital HPV infections usually manifest as benign lesions of the external genital organs (condylomata), they are associated with an increased risk of cancer. Very few data are available on genital HPV infections associated with autoimmune inflammatory diseases or their treatments. Here, we review the published information on this topic.

Deregulation of E-cadherin by human papillomavirus is not confined to high-risk, cancer-causing types

BACKGROUND

E-cadherin is a tumour suppressor protein, which is normally expressed on keratinocytes and antigen-presenting Langerhans cells (LCs) in the epidermis. We have previously shown that E-cadherin is lost from tissues infected with the high-risk cancer-causing human papillomavirus (HPV) type 16.

OBJECTIVES

To test if E-cadherin dysregulation is associated with the cancer risk of the infecting HPV and to establish if it is conserved among HPVs in the α, β, γ and μ genera.

METHODS

Forty-seven lesions infected with low- or high-risk HPV types spanning four HPV genera were stained for E-cadherin, P-cadherin and CD1a to detect LCs.

RESULTS

Surface E-cadherin was reduced in tissues infected with members of the α4, α7 and α9 species and the γ and μ genera but was equivalent to normal epidermis in the β only-infected lesions tested and patchy in α10-infected tissues. There was a direct relationship between atypical E-cadherin expression and a significant reduction in LCs. Expression of P-cadherin, a protein that is increased in the E-cadherin constitutive knockout mouse, was increased in lesions with reduced E-cadherin.

CONCLUSIONS

These data show that E-cadherin dysregulation by HPV is widely conserved across the majority of HPV genera. E-cadherin expression was reduced or lost in epidermis irrespective of the cancer risk of the infecting HPV type or the ability of the virus to degrade retinoblastoma protein or p53. A correlation between dysregulated E-cadherin and reduced numbers of LCs supports viral regulation of surface E-cadherin contributing to viral evasion of the host immune system.

The role of inflammation in HPV carcinogenesis

The role of inflammation in human papillomavirus (HPV) infection and disease is complex since it involves responses capable of preventing initial infections, clearing those ongoing as well as promoting persistence and progression of associated lesions. Avoiding the immune response has been considered a key aspect of HPV persistence which is the main factor leading to HPV-related neoplasia. HPVs have evolved different ways of targeting immune signaling pathways. Moreover, host inflammatory response may promote lesion progression and affect tumor fate by diverse mechanisms including the direct participation of inflammatory cells. In this review, we discuss the interplay between HPV oncogenic proteins and an array of inflammatory responses that ultimately may lead to cancer.

Papillomavirus prophylactic vaccines: established successes, new approaches

Vaccines against the human papillomaviruses (HPVs) most frequently associated with cancer of the cervix are now available. These prophylactic vaccines, based on virus-like particles (VLPs), are extremely effective, providing protection from infection in almost 100% of cases. However, the vaccines present some limitations: they are effective primarily against the HPV type present in the vaccine, are expensive to produce, and need a cold chain. Vaccines based on the minor capsid protein L2 have been very successful in animal models and have been shown to provide a good level of protection against different papillomavirus types. The potential of L2-based vaccines to protect against many types of HPVs is discussed.