Immunological events in regressing genital warts

Imiquimod

PURPOSE OF REVIEW

Imiquimod is the first member of a new class of immune response modifiers; it was first approved in 1997 for the topical treatment of external genital and perianal warts. It is an imidazoquinoline, a novel synthetic compound which is an immune response stimulator, enhancing both the innate and acquired immune pathways (particularly T helper cell type 1-mediated immune responses) resulting in antiviral, antitumour and immunoregulatory activities. The mechanism of action of imiquimod involves cytokine induction in the skin, which then triggers the host's immune system to recognize the presence of a viral infection or tumour, ultimately to eradicate the associated lesion.

RECENT FINDINGS

Imiquimod, a patient-applied topical 5% cream is clinically efficacious and safe in the management of condylomata acuminata and other warty manifestations of human papillomavirus infections. Although not licensed for use against other viral skin infections, preliminary data suggest imiquimod's success against molluscum contagiosum, caused by a poxvirus. Initial studies with imiquimod for the management of HPV-related intraepithelial dysplasias (bowenoid papulosis/vulvar intraepithelial neoplasia) as well as for ultraviolet-induced skin lesions such as actinic keratoses, Bowen's disease, and basal cell carcinomas show great promise in immunocompetent and immunosuppressed patients.

SUMMARY

In the future, imiquimod and newer generations of imidazoquinolines (resiquimod) require further investigation for potential clinical utility in treating other cutaneous and mucosal viral infections, dysplasias and neoplasia, as well as potential vaccine adjuvants.

Effect of vaccine delivery system on the induction of HPV16L1-specific humoral and cell-mediated immune responses in immunized rhesus macaques

There have been numerous studies to assess the immunogenicity of candidate therapeutic and prophylactic vaccines for human papillomavirus (HPV), but few of them have directly compared different vaccines in an immunologically relevant animal system. In the present study, several vaccine delivery systems (VLPs, chimeric VLPs, plasmid DNA, and a replication incompetent adenoviral vector) expressing HPV16L1 were evaluated for their ability to induce HPV16L1 VLP-specific humoral immune responses, including neutralizing antibodies, and cell-mediated immune responses in rhesus macaques. Monkeys immunized with HPV16L1 VLPs mounted a potent humoral response with strongly neutralizing antibodies and a strong L1-specific Th2 response as measured by IL-4 production by CD4+ T cells. Monkeys immunized with plasmid DNA or an adenoviral vector expressing HPV16L1 showed strong Th1/Tc1 responses as measured by IFN-gamma production by CD4+ and/or CD8+ T cells and potent humoral responses, but only weakly neutralizing antibodies. These data demonstrate that the nature of the immune response against HPV16L1 is dramatically different when it is introduced via different delivery systems. Additionally, these findings support the notion that an HPV16L1 VLP-based vaccine will induce the strongly neutralizing antibodies necessary for effective prophylaxis.

Identification and characterisation of a group of cervical carcinoma patients with profound downregulation of intratumoral Type 1 (IFNgamma) and Type 2 (IL-4) cytokine mRNA expression

Type 1 cytokines, such as interferon gamma (IFNgamma) and interleukin-2 (IL-2), increase T cell-mediated immune responses and are considered to be beneficial for antitumour immunity. Type 2 cytokines, such as IL-4, IL-5, and IL-10, inhibit Type 1 responses and promote humoral responses. We have previously reported an association between low intratumoral IFNgamma mRNA levels and poor clinical outcome in patients with invasive cervical carcinoma. In this study, by using quantitative polymerase chain reaction (PCR), we identified a group of cervical carcinoma patients with undetectable intratumoral T cell-derived cytokine mRNAs, as IFNgamma, IL-4 and IL-17 expression could not be detected in 5, 25 and 8 of the 52 biopsies analysed, respectively. Global downregulation of Type 1 and Type 2 cytokines was observed in a subgroup of patients who more frequently presented advanced stage tumours. Biopsies of patients with no IFNgamma gene expression did not appear to be less infiltrated by T cells than control biopsies with measurable IFNgamma gene expression. These results clearly demonstrate that, in some clinical situations, the decrease in intratumoral Type 1 cytokines is not associated with a Type 2 polarisation, but rather reflects global deactivation of T cells at the tumour site. These data provide support for immunotherapy protocols designed to reverse the anergic state of T cells in cancer.

Giant condyloma acuminatum

BACKGROUND

Giant condyloma acuminatum is a warty lesion that is characterized by its large size and propensity to infiltrate into deeper tissues contrasting with its microscopically benign pattern. It is proposed that giant condyloma represents an intermediate lesion between condyloma acuminatum and verrucous carcinoma.

OBJECTIVE

A primary therapeutic option of giant condyloma is radical surgery with or without adjunctive chemotherapy. Because of the tumor's large extent in this case, curative therapy would have been achieved by wide surgical excision.

METHOD

We present a morphologically and histologically classic example of giant condyloma with respect to origin from common genital warts. The reason for extensive exophytic growth was due to delay in therapy because of the patient's self neglect but not due to immune deficiency. The patient was treated with wide surgical excision.

RESULTS

The postoperative period was uneventful, allowing satisfactory functional and cosmetic results.

CONCLUSION

This case is an interesting case because of its exceptionally huge size without any deep tissue involvement and tissue atypia. This suggests that giant condyloma is an intermediate condition that exhibits a continuous tendency for growth.

Repetitive and consistent cervicovaginal exposure to certain viral pathogens appears to protect against their sexual acquisition in some women: potential mechanisms

Several groups have proposed that human female promiscuity or polyandry, with repetitive and consistent cervicovaginal exposure to human immunodeficiency virus type 1 (HIV-1), can lead to protection against sexual acquisition of HIV-1 in some of these women. The mechanism of this phenomenon, the highly exposed persistently HIV-seronegative (HEPS) state, is unknown. Thus far, it has been correlated with viral epitope-specific immune responses in only about half of the women evaluated. But when present, these responses decline rapidly following interruption of pathogen exposure, and correlate with prompt acquisition of HIV. I have extended the concept of HEPS to another sexually transmitted viral pathogen, human papillomavirus (HPV). Supporting clinical and immunological information were identified from a literature search using PubMed as well as several sets of epidemiological data, including longitudinal surveys of HIV-1 incidence among female commercial sex workers (CSWs) in Africa and Thailand, and follow-up of a Danish cohort of CSWs and a large group of Brazilian women, both at high risk for HPV infection. These studies suggest that male-to-female penile-vaginal transmission of at least two viruses, HIV-1 and HPV, is blocked by local mucosal responses, immunologic or otherwise, which require repetitive, uninterrupted exposure to pathogen. Exploration of the mechanisms underlying such ostensibly protective responses may facilitate development of STD vaccines.

HLA class II polymorphisms and susceptibility to recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) is characterised by multiple laryngeal papillomas. Left untreated, the lesions enlarge, spread, and endanger the airway. Medical treatments are unsatisfactory, and repeated surgery remains the mainstay of therapy. RRP is caused by human papillomavirus (HPV) infection. However, since oral HPV infection is common and RRP is rare, other host and/or viral factors may contribute to pathogenesis. In an attempt to identify such factors, we have investigated 60 patients. The patients were HLA class I, II, and tumor necrosis factor TNF typed by sequence-specific primer PCR, and the results compared to those for 554 healthy controls by using Fisher's exact test. Peripheral blood mononuclear cell proliferative responses of 25 controls and 10 patients to HPV-11 L1 virus-like particles (VLP) were compared. Short-term VLP-specific T-cell lines were established, and recognition of L1 was analyzed. Finally, the L1 open reading frames of HPV isolates from four patients were sequenced. Susceptibility to RRP was associated with HLA DRB1*0301 (33 of 60 patients versus 136 of 554 controls, P < 0.0001). The three most severely affected patients were homozygous for this allele. A range of T-cell proliferative responses to HPV-11 VLP were observed in DRB1*0301-positive healthy donors which were comparable to those in DRB1*0301-negative controls. Individuals with juvenile-onset RRP also mounted a range of VLP responses, and their magnitude was negatively correlated with the clinical staging score (P = 0.012 by the Spearman rank correlation). DRB1*0301-positive patients who responded to L1 recognized the same epitope as did matched controls and produced similar cytokines. Sequencing of clinical isolates excluded the possibility that nonresponsiveness was the result of mutation(s) in L1.

Distinct T cell subsets and cytokine production in cultures derived from transformation zone and squamous intraepithelial lesion biopsies of the uterine cervix

PROBLEM

The characterization of lymphocytes issued from squamous intraepithelial lesions (SIL) and from the transformation zone (TZ), where the majority of SIL occur, is important to understand the role of immunity in SIL development.

METHOD OF STUDY

We compared lymphocyte populations of the TZ and SIL with those of normal exocervix, using a technique allowing for the isolation of lymphocytes, either from the epithelium or from the underlying stroma of small biopsies.

RESULTS

The majority of cells derived from the epithelium of all biopsies were CD8+ T cells. Some SIL-derived cultures were characterized by an increased proportion of activated TCRgammadelta+. The production of the immunosuppressive cytokine IL10 was significantly higher in lymphocyte cultures from the normal TZ in comparison with the exocervix. A decreased percentage of effector T cells was observed in cultures derived from the stroma of normal TZ (TCRgammadelta+) or SIL (CD8+) in comparison with the exocervix.

CONCLUSIONS

Our results suggest that a low proportion of effector T cells and IL10 production could contribute to the predisposition of the TZ to the development of SIL and to the progression of SIL to cervical cancer.

Intraepithelial DNA immunisation with a plasmid encoding a codon optimised COPV E1 gene sequence, but not the wild-type gene sequence completely protects against mucosal challenge with infectious COPV in beagles

DNA plasmids encoding the open reading frames of canine oral papillomavirus (COPV) nonstructural early genes E1, E2, or E7 protein were delivered into both oral mucosal and cutaneous epithelial sites in beagle dogs using particle-mediated immunotherapeutic delivery (PMID) technology. Control dogs were vaccinated with plasmid encoding either hepatitis B virus surface antigen (HBVs) or COPV L1. Using a prophylactic immunisation protocol, a priming dose of plasmid DNA was followed by a booster dose 6 weeks later. Four weeks after boost, all dogs were challenged with infectious COPV particles. Following viral challenge, as shown previously (M. A. Stanley et al., 2001, Vaccine 19, 2783-2792), mucosal papillomas developed in the negative-control HBVs vaccinated dogs, but all animals in the COPV L1 group were fully protected from disease development. In the early gene-vaccinated groups five of six in the E1-vaccinated dogs, two of six in E2-vaccinated dogs, and three of six in the E7-vaccinated beagles developed oral papillomas. Compared to the HBVs negative-control group the oral papillomas that did develop in the early-gene vaccinated beagles were significantly smaller, shorter in duration, and fewer in number. Taken together the disease burden was markedly reduced and this was statistically significant. In a second experiment one group of animals was vaccinated with plasmid encoding the wild-type COPV E1 gene, and a separate group was vaccinated with plasmid encoding a synthetic codon-optimised COPV E1 gene sequence. None of the codon-optimised E1-vaccinated animals developed papillomas at any challenge site. However, all animals vaccinated with wild-type E1 had papillomas. These data suggest that immunisation by PMID with papillomavirus early genes can significantly impact upon subsequent disease development and that full protection can be achieved using improved vectors encoding codon-optimised gene sequences perhaps emphasizing the importance of antigen load in the generation of protective responses to papillomavirus proteins.

The status of HPV16-specific T-cell reactivity in health and disease as a guide to HPV vaccine development

Human papilloma viruses (HPV) are among the most common sexually transmitted pathogens in young adults. In the majority of individuals, anti-viral immunity is capable of suppressing viral infection but in a minority of patients viral infection is not cleared in time to prevent the development of malignancies. In these cases, HPV16-specific immunity may develop too late, is not strong enough, and/or is possibly of the wrong type. The influence of pre-existing immunity on the efficacy of vaccines is largely unknown. Nor has it been studied what the effect is of vaccines on the various types of pre-existing HPV-specific T-cell immunity. Animal models showing that vaccines are able to protect against a subsequent tumor challenge and even to treat transplantable tumors, are not qualified to address this point because tumor development is not preceded by persistent viral infection. Therefore, the comparison between fully characterized pre-existing HPV-specific immunity in patients and healthy subjects is a prerequisite for the full appreciation of vaccine-efficacy as well as for further development of next-generation vaccines.

Imiquimod and the imidazoquinolones: mechanism of action and therapeutic potential

A central development of the past decade has been in our understanding of the interactions between, and interdependence of, the innate and adaptive immune responses. Innate immunity recognizes 'danger' signals and activates adaptive immunity in a targeted, appropriate and effective response. Dendritic cells and macrophages have a central role in this process, and pharmacological agents that modulate the functions of these cells could have therapeutic value. The imidazoquinolone compounds, of which imiquimod, formulated as Aldara trade mark, is the best characterized to date, are such molecules. Imiquimod and its homologues act by activating macrophages and other cells via binding to cell surface receptors, such as Toll receptor 7, thereby inducing secretion of pro-inflammatory cytokines, predominantly interferon (IFN)-alpha, tumour necrosis factor (TNF)-alpha and interleukin (IL)-12. This locally generated cytokine milieu biases towards a Th1 cell mediated immune response with the generation of cytotoxic effectors, and this has been exploited clinically in the treatment of viral infections (human papillomavirus, herpes simplex virus, molluscum contagiosum) and nonmelanoma skin cancer. Imiquimod has been shown to be significantly more effective than placebo in clearing genital warts, and mechanism of action studies indicate that this is related to the ability to generate proinflammatory cytokines and a Th1 response. Intra-epithelial neoplasms of cutaneous and mucosal surfaces are associated with human papillomavirus infection and there is some evidence that immune response modifiers may have therapeutic value for these lesions. Topical immunotherapy with immunomodulators shows potential for effective and patient-friendly treatment of cutaneous viral infections. These compounds also have adjuvant properties that could significantly enhance conventional vaccine strategies.

Treatment of anogenital warts with imiquimod 5% cream followed by surgical excision of residual lesions

Cytodestructive or surgical therapy for patients with anogenital warts is frequently associated with recurrence. In February 1997, the US Food and Drug Administration approved imiquimod as a 5% cream for the treatment of anogenital warts. Activity of the drug results primarily from interferon alfa and other cytokine induction in the skin. These cytokines stimulate several other aspects of the innate immune response. In addition, imiquimod stimulates acquired immunity, in particular the cellular arm that is important for control of viral infections and tumors. Published studies indicate that imiquimod results in complete clearance of warts in more than 50% of patients. Residual warts can be surgically excised. Our long-term follow-up (ie, 2 to 7 years) of patients who had a 16-week course of imiquimod cream with subsequent removal of remaining warts showed a much lower rate of recurrence in comparison with those patients who were treated with surgery alone. Therefore, treatment with imiquimod followed by excision of residual lesions may provide long-term clearance of anogenital warts in those patients in whom imiquimod monotherapy is insufficient.

Evasion of host immunity directed by papillomavirus-encoded proteins

The nature of the interaction between papillomaviruses (PV) and their infected host has led to the identification of ways in which the viral oncoproteins can transform the infected host cells into cancer cells. As viral persistence is required for malignancy, and persistence requires avoidance of immune attack by the host, defining the relationship between PV and the immune system is also paramount in understanding tumorigenesis. It has emerged that PV have evolved several ways in which to prevent clearance by the host immune system. The limitation of the PV replication cycle to the epithelium, together with low level expression of the virus proteins and an absence of inflammation, minimises the exposure of virus to immune cells. In addition, more recently it has been shown that, like many other viruses, PV can directly subvert the immune response, including interference with the interferon pathway, modulation of antigen presentation, inhibition of interleukin-18 activity and down-regulation of major histocompatibility class I on infected cells. Collectively these mechanisms explain how PV lesions are able to persist for long periods of time in immunocompetent hosts.

Priming of human papillomavirus type 11-specific humoral and cellular immune responses in college-aged women with a virus-like particle vaccine

In this study, we evaluated the potency of a human papillomavirus (HPV) virus-like particle (VLP)-based vaccine at generating HPV type 11 (HPV-11)-specific cellular and humoral immune responses in seronegative women. The vaccine was administered by intramuscular immunizations at months 0, 2, and 6. A fourth immunization was administered to approximately half of the women at month 12. All vaccine recipients had positive HPV-11 VLP-specific lymphoproliferative responses at month 3 following the second immunization (geometric mean lymphoproliferative stimulation index [SI] = 28.4; 95% confidence interval [CI] = 16.9 to 48.0) and HPV-11 VLP-specific antibody titers following the first immunization at month 1 (geometric mean antibody titer = 53.9 milli-Merck units/ml, 95% CI, 34.8 to 83.7). In contrast, lymphoproliferative and antibody titer responses were never detected in the participants who received placebo. Relatively homogeneous lymphoproliferative responses were observed in all vaccinated women. The mean lymphoproliferative SI of the vaccinated group over the first 12 months of the study was 7.6-fold greater than that of the placebo group following the initial immunization. The cellular immune responses generated by VLP immunization were both Th1 and Th2, since peripheral blood mononuclear cells from vaccinees, but not placebo recipients, secreted interleukin 2 (IL-2), IL-5, and gamma interferon (IFN-gamma) in response to in vitro stimulation with HPV-11 VLP. The proliferation-based SI was moderately correlated with IFN-gamma production and significantly correlated with IL-2 production after the third immunization (P = 0.078 and 0.002, respectively). The robust lymphoproliferative responses were specific for HPV-11, since SIs generated against bovine papillomavirus and HPV-16 VLPs were not generally observed and when detected were similar pre- and postimmunization.

Analysis of CD4(+) T-cell responses to human papillomavirus (HPV) type 11 L1 in healthy adults reveals a high degree of responsiveness and cross-reactivity with other HPV types

Human papillomavirus type 11 (HPV-11) infection causes genital warts and recurrent respiratory papillomatosis. While there is compelling evidence that CD4(+) T cells play an important role in immune surveillance of HPV-associated diseases, little is known about human CD4(+) T-cell recognition of HPV-11. We have investigated the CD4(+) T-cell responses of 25 unrelated healthy donors to HPV-11 L1 virus-like particles (VLP). CD4(+) T-cell lines from 21 of 25 donors were established. Cell sorting experiments carried out on cells from six donors demonstrated that the response was located in the CD45RA(low) CD45RO(high) memory T-cell population. To determine the peptide specificity of these responses, epitope selection was analyzed by using 95 15-mer peptides spanning the entire HPV-11 L1 protein. No single region of L1 was immunodominant; responders recognized between 1 and 10 peptides, located throughout the protein, and peptide responses fell into clear HLA class II restricted patterns. Panels of L1 peptides specific for skin and genital HPV were used to show that the L1 CD4(+) T-cell responses were cross-reactive. The degree of cross-reactivity was inversely related to the degree of L1 sequence diversity between these viruses. Finally, responses to HPV-11 L1 peptides were elicited from ex vivo CD45RO(+) peripheral blood mononuclear cells, demonstrating that recognition of HPV-11 was a specific memory response and not due to in vitro selection during tissue culture. This is the first study of CD4(+) T-cell responses to HPV-11 in healthy subjects and demonstrates marked cross-reactivity with other skin and genital HPV types. This cross-reactivity may be of significance for vaccine strategies against HPV-associated clinical diseases.

The impact of HIV infection and immunodeficiency on human papillomavirus type 6 or 11 infection and on genital warts

BACKGROUND

HIV infection and associated immunodeficiency are known to alter the course of human papillomavirus (HPV) infections and of associated diseases.

GOAL

This study investigated the association between HIV and HPV and genital warts.

STUDY DESIGN

HPV testing and physical examinations were performed in two large prospective studies: the Women's Interagency HIV Study (WIHS) and the HIV Epidemiology Research Study (HERS). Statistical methods incorporating dependencies of longitudinal data were used to examine the relationship between HIV and HPV and genital warts.

RESULTS

A total of 1008 HIV-seronegative and 2930 HIV-seropositive women were enrolled in the two studies. The prevalence of HPV 6 or 11 was 5.6 times higher in HIV-seropositive women in the WIHS and 3.6 times higher in the HERS. Genital wart prevalence increased by a factor of 3.2 in the WIHS and 2.7 in the HERS in HIV-seropositive women. In the WIHS, infection with HPV type 6 or 11, in comparison with no HPV infection, was associated with odds of genital wart prevalence of 5.1 (95% CI: 2.9-8.8), 8.8 (95% CI: 6.1-12.8), and 12.8 (95% CI: 8.8-18.8) in HIV-seronegative women, HIV-seropositive women with > or =201 CD4 cells/microl, and HIV-seropositive women with < or =200 CD4 cells/microl, respectively. In the HERS, infection with HPV type 6 or 11 was associated with odds of 2.7 (95% CI: 1.6-4.6), 4.9 (95% CI: 3.2-7.7), and 5.3 (95% CI: 3.3-8.5) in these same groups. Other HPV types showed a similar dose-response relation, but of substantially lower magnitude and statistical significance.

CONCLUSIONS

HIV infection and immunodeficiency synergistically modified the relation between HPV 6 or 11 infection and genital wart prevalence.

Established human papillomavirus type 16-expressing tumors are effectively eradicated following vaccination with long peptides

Peptide-based vaccines aimed at the induction of effective T cell responses against established cancers have so far only met with limited clinical success and clearly need to be improved. In a preclinical model of human papillomavirus (HPV)16-induced cervical cancer we show that prime-boost vaccinations with the HPV16-derived 35 amino-acid long peptide E7(43-77), containing both a CTL epitope and a Th epitope, resulted in the induction of far more robust E7-specific CD8(+) T cell responses than vaccinations with the minimal CTL epitope only. We demonstrate that two distinct mechanisms are responsible for this effect. First, vaccinations with the long peptide lead to the generation of E7-specific CD4(+) Th cells. The level of the induced E7-specific CD8(+) T cell response proved to be dependent on the interactions of these Th cells with professional APC. Second, we demonstrate that vaccination with the long peptide and dendritic cell-activating agents resulted in a superior induction of E7-specific CD8(+) T cells, even when T cell help was excluded. This suggests that, due to its size, the long peptide was preferably endocytosed, processed, and presented by professional APCs. Moreover, the efficacy of this superior HPV-specific T cell induction was demonstrated in therapeutic prime-boost vaccinations in which the long peptide admixed with the dendritic cell-activating adjuvant oligodeoxynucleotide-CpG resulted in the eradication of large, established HPV16-expressing tumors. Because the vaccine types used in this study are easy to prepare under good manufacturing practice conditions and are safe to administer to humans, these data provide important information for future clinical trials.

Therapeutic vaccination against chronic viral infections

Chronic viral infections such as those caused by hepatitis B virus, human papilloma virus, herpes simplex virus, and HIV, in theory, present logical targets of active specific immunotherapy. Indeed, immunological mechanisms are involved in several aspects of their pathogenesis and natural course, such as virus persistence, destruction of infected cells and control of viral replication. Therapeutic vaccination could therefore be an adequate replacement for, or adjunct to, existing therapies. Almost all approaches to therapeutic vaccination have been evaluated in those four disease areas. Despite encouraging results in animals none of these attempts has, so far, been completely successful in the human setting. However, with a better understanding of the immunological mechanisms involved in the control of disease successful therapeutic vaccines, used alone or in combination with other therapies, are an achievable goal.

Human papillomavirus update with a particular focus on cervical disease

Human papillomavirus (HPV) is a common viral infection of squamous epithelial tissues, but its importance has only recently been recognised by the medical community. HPVs are now realised to consist of many genotypes and are associated with a diverse spectrum of clinical manifestations. Within the genital tract, some diseases have been recognised since antiquity; for example, genital warts which are caused by HPV types distinct from those causing genital cancer. However, others (such as cervical cancer), although recognised centuries ago as linked to sexual activity, have only been associated with oncogenic HPVs relatively recently, with the tools of molecular biology. We now understand that genital HPV infections are the most common sexually transmitted viral infections, are largely transient, asymptomatic and of no consequence. This virus manifests as more than just benign warts. Chronic carriage of with oncogenic genotypes (over years and in a minority of patients), together with other cofactors (host and/or exogenous) in complex pathways not totally understood, result in severe dysplasia or, ultimately, carcinogenesis. As it takes time for precursor lesions to develop and there are effective screening programmes for their detection and treatment, HPV-related neoplastic disease of the cervix is largely a preventable reproductive health issue of women. Yet, on a global scale, cervical cancer is the second most common cancer of women, with the majority of cases occurring in developing countries. Although HPV is noncultivatable by traditional diagnostic virological methods, successfully applied molecular biology techniques have underpinned development of vaccines which are now in phase II/III clinical trials. Successful vaccination ultimately has the greatest potential to impact upon the global burden of disease from genital HPV infection. However, the outcome from reduction in incidence of dysplasia and neoplasia will take years to eventuate; consequently, various cervical cancer prevention strategies still need to be endorsed and maintained in the meantime.

Verruca vulgaris with CD30-positive lymphoid infiltrate: a case report

Expression of CD30 has been reported in reactive lymphoid cells that accompany some cutaneous viral infections. It is interpreted as a marker of lymphocyte activation in response to the infecting virus. We report on a case of viral wart presenting with an inflammatory infiltrate with numerous CD30+ atypical lymphoid cells. These cells comprised approximately 10% of the reactive cell population and showed a T-helper phenotype. Infection by human papillomavirus should be included among the causes of cutaneous CD30+ reactive lymphoid infiltrates.

The use of vaccines in the prevention and treatment of cervical cancer

The close association between high risk HPV infection and cervical carcinoma has provided the impetus for the development of prophylactic and therapeutic vaccination schedules. An effective prophylactic vaccine would obviate the need for population-based cervical screening programmes, while therapeutic vaccination might provide an effective adjunct to or replacement for conventional treatment for benign and malignant cervical disease. While the challenges associated with the design and implemention of immunotherapies are numerous, optimism remains high and it is expected that the next few decades will witness a revolutionary change in the way we treat cervical cancer and its premalignant lesions. A papillomavirus vaccine that prevented HPV infection on the one hand and acted against established disease on the other, would have a profound impact on one of the major cancers affecting women globally.

Human papillomavirus molecular biology and pathogenesis

Human papillomavirus (HPV) infection is the most common sexually transmitted disease in the world and accounts for an estimated 11% of the global cancer incidence in women. HPV-16 is the most prevalent type detected in cervical cancer and along with types 18, 31, 33 and 45 has been classified as a class I carcinogen. In addition to cervical cancer, HPVs are also associated with the malignant transformation of other mucosal and skin cancers. Thus, the combination of the malignant potential of HPV and its high prevalence of infection confers to it an importance of generalized clinical and virological significance. The natural history of HPV infection with or without treatment varies from spontaneous regression to persistence. The most important mechanism for wart regression appears to be cell-mediated immunity. Cytokines released by keratinocytes or cells of the immune system may play a part in the induction of an effective immune response against HPV infection and the subsequent regression of lesions. This review discusses the molecular biology, pathogenesis and immunology of HPV infections.

The effects of 5% imiquimod cream on high-grade vulval intraepithelial neoplasia

OBJECTIVES

The aim of this study was to investigate the effects of topical 5% Imiquimod (3M Pharmaceuticals, St. Paul, Minnessota) on high-grade vulval intraepithelial neoplasia (VIN).

METHODS

A prospective uncontrolled observational study was performed. Fifteen patients with histologically confirmed VIN 3 were asked to self-administer 5% Imiquimod cream to their vulval lesions up to three times weekly for 16 weeks. Review was conducted at 1, 2, 3, 4, 6, and 9 months postrecruitment. Lesions were photodocumented and at 4 months any areas demonstrating a clinical response were biopsied.

RESULTS

Of 15 patients recruited, 4 demonstrated a clinical improvement in their disease, 3 of whom had negative biopsies posttreatment. Local side effects limited the frequency of application such that 7 patients applied the cream once weekly, 6 twice weekly, and 2 three times weekly.

CONCLUSIONS

5% Imiquimod cream appears to have an effect when used on high-grade VIN. The frequency of application was limited by local side effects which may have reduced the clinical responses seen. Measures to alleviate local side effects may allow more aggressive use of Imiquimod and lead to improved responses.

Immunity to oncogenic human papillomaviruses

The establishment of human papillomavirus (HPV) infection as a major cause of several human cancer forms, notably cervical cancer, has spurred development of prophylactic and/or therapeutic HPV vaccines for prevention of cervical neoplasia. Knowledge of the immunity to HPV forms the basis for such endeavors.

METHOD

A literature review of humoral and cellular immunity to HPV. The overview on human leukocyte antigen (HLA) and cervical cancer was expanded to a formal metaanalysis, where relevant articles were located by Medline search and citation analysis and graded by preassigned quality criteria on study design.

RESULTS

The antibody response to the HPV particle is dominated by a neutralizing antibody response to a typespecific, conformationally dependent immunodominant epitope. Vaccines based on viral particles lacking the viral genome (virus-like particles, VLPs) have been highly successful in preventing and treating HPV infection in several animal model systems. In humans, the serum antibody response to VLPs is stable over time, also after the HPV infection has been cleared, resulting in HPV serology being used as a marker of cumulative HPV exposure in spite of the fact that a significant proportion of HPV-exposed subjects fail to seroconvert. More than 90% of HPV infections will clear spontaneously. The factors that determine whether an HPV infection is cleared or persists and increases the risk for cancer are not known, but cellular immunity is implicated. Several HLA class II haplotypes are associated with cervical cancer: DQw3 increases and DR13 decreases the risk for cervical cancer in general (odds ratios (OR) and 95% confidence intervals (CI): 1.25(1.15-1.37) and 0.69 (0.56-0.85), respectively); DR15 increases the risk for HPV16-carrying cancer (OR: 1.47; CI: 1.20-1.81); and DR7 may be either protective or increase the risk. Most cervical cancers have downregulated the expression of at least one HLA class I antigen, whereas class II expression is increased in infected epithelium. A Th2 cytokine profile is associated with progression to cervical cancer. HPV-antigen-specific proliferative responses have been detected in many studies, although it is not entirely clear whether these responses are HPV type specific or may be cross-reactive between HPV types. Specific cytotoxic T lymphocyte (CTL) responses were originally reported in only a minority of infected subjects, typically cancer patients, but with advancing technology, specific CTLs can be stimulated from about half of the women with HPV-carrying disease. In animal model systems, CTL responses can mediate clearance.

CONCLUSION

The antibody response to HPV is a mediator of type-specific protective immunity, which forms the basis for prophylactic vaccine candidates. The cellular immunity to HPV is implicated as an important factor in cervical carcinogenesis, but the main targets and types of responses that mediate HPV clearance are not established.

Effect of adjuvant imiquimod 5% cream on sustained clearance of anogenital warts following laser treatment

OBJECTIVES

Imiquimod is an immune response modifier that has demonstrated a good efficacy and relatively low recurrence rates in comparison to other genital wart treatment modalities. The primary objective of this open-label study was to evaluate the effect on sustained clearance of treated lesions and the safety of patient-applied topical imiquimod after laser therapy of external anogenital warts.

METHODS

After laser treatment of visible external anogenital warts the ablated region(s) were treated with imiquimod 5% cream three times/week over 12 weeks beginning when the wound healing process was completed, followed by a six-month treatment-free observation period for the assessment of sustained clearance of treated lesions.

RESULTS

A total of 211 male and female patients was enrolled in the study. After 12 weeks of treatment, 65.4% of all patients showed sustained clearance. During the treatment period, 15 patients (7.1% of 211 patients) presented with recurrent warts in the treated areas, and 58 (27.5%) patients were excluded for other reasons. During the six-month follow-up period, ten additional patients (7.3% of 138 patients) developed wart recurrences. The application of imiquimod 5% cream was well tolerated. The number of patients with adverse events related to study medication declined from the first month of treatment until the end of the third month. Most frequently, mild to moderate itching, burning, pain and erythema were reported.

CONCLUSIONS

After laser therapy and sufficient wound healing, administration of imiquimod 5% cream three times/week appears to be safe and to reduce the incidence of wart recurrences.

Imiquimod 5% cream is an acceptable treatment option for external anogenital warts in uncircumcised males

OBJECTIVES

To determine the safety and efficacy of imiquimod (Aldara) 5% cream in the treatment of prepuce-associated warts in uncircumcised males.

METHODS

An open-label study in six UK medical centres with 35 uncircumcised males with prepuce-associated warts treated with imiquimod 5% cream three times per week for up to 16 weeks. Other anogenital warts were also treated.

RESULTS

Three times weekly application of imiquimod was found to be safe, with erythema as the most commonly reported local skin reaction. Forty per cent of patients had complete clearance of anogenital warts within 16 weeks.

CONCLUSIONS

Imiquimod cream at a dosing regimen of three times per week, is effective and has an acceptable safety profile in the treatment of prepuce associated warts and other external anogenital warts in uncircumcised males.

Imiquimod 5% cream is a safe and effective self-applied treatment for anogenital warts--results of an open-label, multicentre Phase IIIB trial

Our objective was to determine the efficacy and safety of imiquimod 5% cream in the treatment of external genital/perianal warts in an open-label Phase IIIB trial. Patients applied imiquimod 5% cream 3 times per week, for up to 16 weeks. Those who cleared their warts were monitored during a 6-month follow-up period. If their warts recurred, or new warts developed during this time, patients could be re-treated for up to 16 additional weeks. Patients who experienced partial clearance during the initial treatment period entered an extended treatment period of up to an additional 16 weeks. A total of 943 patients from 114 clinic sites in 20 countries participated in this study. Complete clinical clearance was observed in 451/943 (47.8%) patients (intent-to-treat (ITT) analysis) during the initial treatment period, with clearance in an additional 52 (5.5%) patients during the extended treatment period beyond 16 weeks. The overall clearance rate for the combined treatment periods was 53.3%. In a treatment failure analysis, the overall clearance rate was 65.5%; a greater proportion of female patients (75.5%) experienced complete clearance than male patients (56.9%). Low recurrence rates, of 8.8% and 23.0%, were observed at the end of the 3- and 6-month follow-up periods, respectively. The sustained clearance rates (patients who cleared during treatment and remained clear at the end of the follow-up period) after 3 and 6 months were 41.6% and 33.0% (ITT analysis), respectively. Local erythema occurred in 67% of patients. In the majority of patients local skin reactions were of mild to moderate severity. In conclusion, imiquimod 5% cream is an effective self-applied treatment for external genital/perianal warts when applied for up to 16 weeks and is well tolerated for up to 32 weeks.

Dendritic cells induce the death of human papillomavirus-transformed keratinocytes

Although human papillomavirus (HPV) antigens are expressed in a majority of (pre)neoplastic lesions (squamous intraepithelial lesions; SILs) of the uterine cervix, progression to invasive cancer may occur, which suggests that the presentation of viral antigens to the immune system is deficient in some SILs. To determine whether professional antigen-presenting cells die in SILs, we assayed for the apoptosis of immature dendritic cells (DC) in organotypic cultures of HPV-transformed keratinocytes, which reproduce many features of in vivo observed SILs. Unexpectedly, the infiltration of organotypic cultures by DC specifically induced the apoptosis of HPV+ tumor cells, whereas DC were not affected. In the same conditions and in coculture experiments, apoptosis was not observed in normal keratinocytes. The induction of apoptosis required membrane contacts between DC and HPV-transformed keratinocytes. Although the HPV+cell lines were sensitive to the effects of TRAIL, soluble TRAILR2-Fc did not block the DC-induced apoptosis. Furthermore, although FasL and Fas were detected on DC and HPV+ cell lines, respectively, functional analysis revealed that this pathway is not responsible for the apoptosis induced by the DC. All together these results suggest that DC may be at the interface between innate and adaptive immunity by inducing the apoptosis of (pre)neoplastic cells.

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.

Topical immunomodulators--progress towards treating inflammation, infection, and cancer

Immunomodulators include both immunostimulatory and immunosuppressive agents. Only recently have the basic mechanisms of topical immunotherapy been elucidated. Besides topical contact sensitisers (eg, diphencyprone or dinitrochlorobenzene), newer agents of the imidazoquinoline family such as imiquimod and resiquimod act by inducing cytokine secretion from monocytes or macrophages (interferon-alpha, interleukin-12, tumour-necrosis factor-alpha). The locally generated immune milieu leads to a Th1-dominance and cell-mediated immunity that have been used clinically to treat viral infections such as human papillomavirus (HPV), herpes simplex virus (HSV), mollusca, and cancerous lesions including initial squamous cell and basal cell carcinoma in immunocompetent and immunosuppressed patients. While these agents improve antigen-presentation by dendritic cells, they also act on B cells and lead to the synthesis of antibodies such as IgG2a much like the recently discovered immunostimulatory CpG-sequences that stimulate innate immunity. These sequences act as "danger signals" since they occur in bacterial and viral DNA, but are selectively methylated and inactivated in the mammalian genome. They share the induction of the same cytokines as imidazoquinolines but they show different magnitudes and kinetics of response. Topical immunotherapy with immunostimulatory agents shows potential for effective and patient-friendly treatment of inflammatory, infectious, and cancerous skin diseases. Immunoenhancers such as imdazoquinolines and CpG-sequences also have adjuvant properties that could improve conventional (protein) and DNA vaccination against cancer, atopy, and allergies.

The treatment of human papillomavirus lesions of the lower genital tract

Anogenital warts are caused by human papillomavirus types 6 and 11 infection, and are the most common clinical manifestation of lower genital tract human papillomavirus infection. They are the most frequently recognized sexually transmitted disease in the developed world, occurring at an incidence rate of 0.5-1.2% in young men and women aged 18-25 years. Many therapies for genital warts have been described, none being ideal in that all therapeutic modalities fail to clear the warts in a proportion of patients, and the recurrence of warts after successful treatment is seen with all treatments. The current knowledge base of the therapy of genital warts is flawed by a lack of good natural history data either with treatment or without treatment over longer periods of time, in that most trials report comparisons of monotherapies over a short time and there is a lack of structured trials addressing consecutive therapies over longer durations, as occurs in real-life clinical situations.

Quantitative analysis of IL-10 and IFN-gamma mRNA levels in normal cervix and human papillomavirus type 16 associated cervical precancer

Human papillomavirus type 16 is a major factor in cervical carcinogenesis. Inappropriate cytokine synthesis may direct the local immune response away from a type-1 (cellular) pattern and may subsequently contribute to the development and progression of precancer. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) using a competitive mimic was carried out to determine type-1 (interferon gamma (IFN-gamma)) and type-2 (interleukin-10 (IL-10)) cytokine mRNA levels in whole cervical specimens (without microdissection) from seven normal and nine HPV-16 positive CIN formalin-fixed paraffin-embedded tissues. Microdissection was used to measure separately the epithelial and sub-epithelial levels of IFN-gamma and IL-10 mRNAs in 11 specimens of normal cervix and 25 HPV-16 positive CIN (nine CIN 1, seven CIN 2 and nine CIN 3). IFN-gamma mRNA was lower in CIN than normal (p=0.04). IL-10 mRNA level in CIN was significantly higher (p=0.005) than in normal cervix (before microdissection). Epithelial IFN-gamma mRNA showed a significant decrease in all grades of CIN (median=3.58) compared with normal (7.74) (p<0.05), but there was no significant difference between the grades. A significant decrease in sub-epithelial IFN-gamma mRNA was found in CIN 1(9.81), CIN 2 (3.82) and CIN 3 (4.62) compared with normal cervix (27.35) (p<0.05). Also, sub-epithelial IFN-gamma mRNA was significantly lower in CIN 2 and CIN 3 than in CIN 1 (p=0.005 and 0.0005, respectively). IL-10 was detected in the epithelium of only one of 11 normal and one of 25 CIN, but sub-epithelial IL-10 was significantly higher in CIN 2 (0.08) and CIN 3 (0.26) than in normal (0.00) (p=0.036 and 0.0032, respectively). There was no significant difference in the sub-epithelial level of IL-10 between normal and CIN 1 (0.00) (p=0.96). Our results suggest that reduced epithelial and sub-epithelial IFN-gamma, as well as increased sub-epithelial IL-10 synthesis may play a role in the development and progression of HPV-16 associated cervical precancer.

Antibody, cytokine and cytotoxic T lymphocyte responses in chimpanzees immunized with human papillomavirus virus-like particles

We evaluated antibody, cytokine (IFN-gamma, IL-5, TNF-alpha), and cytotoxic T lymphocyte (CTL) responses in chimpanzees immunized with monovalent or quadrivalent (HPV-6, -11, -16, -18) L1 virus-like particle (VLP) vaccines administered i.m. on aluminum hydroxyphosphate (alum) at weeks 0, 8 and 24. Maximum serum antibody titers to type-specific, neutralizing, conformational epitopes on HPV-11 or -16 L1 VLPs were detected by radioimmunoassay (RIA) four weeks after the second and third immunizations. HPV-11 and -16 neutralizing antibodies were also detected at similar time points with an Human papillomaviruses (HPV) neutralization assay using pseudovirions. Depending on the VLP type used for immunization, HPV type-specific cytokine responses were most frequently seen four weeks after the second or third immunizations and between weeks 44-52. Transient HPV-16 L1-specific CTL activity was observed only between weeks 16-24 in 3 of 22 (13.6%) chimpanzees immunized with HPV-16 L1 VLPs. These findings provide evidence that immunization with multivalent L1 VLPs on alum can evoke both neutralizing antibodies and Th1 and Th2 cytokine responses to several HPV types; however, induction of CTLs is infrequent.

Pre-clinical safety and efficacy of TA-CIN, a recombinant HPV16 L2E6E7 fusion protein vaccine, in homologous and heterologous prime-boost regimens

Human papillomavirus (HPV) E6 and E7 oncoproteins are attractive targets for T-cell-based immunotherapy of cervical intraepithelial neoplasia (CIN) and cancer. A newly designed vaccine, comprising the HPV16 L2, E6 and E7 as a single fusion protein (TA-CIN), was shown to elicit HPV16-specific CTL, T-helper cells and antibodies in a pre-clinical mouse model. These immune responses effectively prevented outgrowth of HPV16-positive tumour cells in a prophylactic setting as well as in a minimal residual disease setting. CTL immunity was optimally induced when TA-CIN was employed in heterologous prime-boost regimens in combination with TA-HPV, a clinical grade vaccinia-based vaccine. These data provide a scientific basis for the use of TA-CIN, alone or in combination with TA-HPV in future human trials.

Regression of canine oral papillomas is associated with infiltration of CD4+ and CD8+ lymphocytes

Canine oral papillomavirus (COPV) infection is used in vaccine development against mucosal papillomaviruses. The predictable, spontaneous regression of the papillomas makes this an attractive system for analysis of cellular immunity. Immunohistochemical analysis of the timing and phenotype of immune cell infiltration revealed a marked influx of leukocytes during wart regression, including abundant CD4+ and CD8+ cells, with CD4+ cells being most numerous. Comparison of these findings, and those of immunohistochemistry using TCRalphabeta-, TCRgammadelta-, CD1a-, CD1c-, CD11a-, CD11b-, CD11c-, CD18-, CD21-, and CD49d-specific monoclonal antibodies, with previously published work in the human, ox, and rabbit models revealed important differences between these systems. Unlike bovine papillomavirus lesions, those of COPV do not have a significant gamma/delta T-cell infiltrate. Furthermore, COPV lesions had numerous CD4+ cells, unlike cottontail rabbit papillomavirus lesions. The lymphocyte infiltrate in the dog resembled that in human papillomavirus lesions, indicating that COPV is an appropriate model for human papillomavirus immunity.

HPV16 L1E7 chimeric virus-like particles induce specific HLA-restricted T cells in humans after in vitro vaccination

Cervical cancer has been shown to be highly associated with human papillomavirus (HPV) infection. The viral oncogenes E6 and E7 are constantly expressed by the tumor cells and are therefore targets for immunotherapy. In the present study we investigated the potential of HPV16 L1E7 chimeric virus-like particles (CVLP) to activate specific cytotoxic T lymphocytes in human blood donors. CVLP were expressed by recombinant baculovirus and purified. Direct incubation of freshly isolated peripheral blood lymphocytes (PBL) with CVLP resulted in induction of proliferation and growth of T cell lines. To enhance antigen presentation we also loaded dendritic cells with CVLP and used them to activate naive T cells. Growing cell lines were mainly CD3 positive (>95%) with a predominant CD4-positive and a minor CD8-positive component. Analysis of Tcell specificity was carried out by an interferon-gamma ELISpot assay. Dendritic cells pseudoinfected with CVLP or pulsed with human leukocyte antigen (HLA)-A*0201-restricted peptide E7(11-20) or with a newly identified HPV16 peptide L1(323-331) were used as stimulator cells. T cells responsive to CVLP were found in the cultures with frequencies of 0.5%-0.7%. Frequencies to peptides were around 0.1%. These T cells had cytolytic activity toward autologous B-lymphoblastic cell lines either pseudoinfected with CVLP or pulsed with HLA-A*0201-restricted peptides. They also lysed the HPV16- and HLA-A*0201-positive cervical cancer cell line CaSki, whereas HLA-A*0201-negative SiHa cells were not lysed. We conclude from our data that CVLP show promise for a therapeutic vaccine in patients with HPV16-positive cervical intraepithelial neoplasia lesions or cervical cancer.

Treatment of external genital warts in men using 5% imiquimod cream applied three times a week, once daily, twice daily, or three times a day

BACKGROUND

Medical therapy for genital warts remains suboptimal. The topical interferon and cytokine inducer, imiquimod, has been proved effective for the treatment of external genital and perianal warts, but there is a substantial difference in the response rates between men and women. When 5% imiquimod cream is applied three times a week up to 16 weeks, approximately two thirds of women treated with imiquimod achieve complete clearance of genital warts, whereas only about one third of men clear completely.

GOAL

This study was undertaken to determine whether more frequent application of topical imiquimod cream would improve the rate of genital wart clearance in men.

STUDY DESIGN

A randomized treatment trial involving adult men with biopsy-proven genital warts was conducted at nine centers in the United States and Canada using four different application frequencies.

RESULTS

Complete clearance rates during the 16-week treatment period were as follows for the different imiquimod treatment frequencies: three times a week (35 %), once daily (28 %), twice daily (24%), and three times a day (27%)(P = 0.88). The four treatment groups all showed comparable reductions in the total lesion area, with a median of more than a 90% reduction in the lesion area by the end of treatment. There was a significant increase in the incidence and severity of local skin reactions including erythema, vesicle formation, ulceration, and excoriation as the dosing frequency increased from three times a week to three times a day.

CONCLUSIONS

In this study, the optimal dosage regimen was the approved three times a week regimen. More frequent application (up to three times a day) did not improve clearance and was associated with an increase in local adverse events.

Identification of genes induced by a macrophage activator, S-28463, using gene expression array analysis

S-28463 and imiquimod are imidazoquinoline compounds which stimulate microbicidal activity by inducing a local immune response at the site of application. Imiquimod-containing cream is an effective clinical treatment against cervical warts caused by human papillomavirus infection. Imiquimod also induces leishmanicidal activity both in vitro in macrophages and in vivo in a mouse model for cutaneous leishmaniasis. The major target cells of S-28463 and imiquimod are macrophages. To explore the molecular basis in which imidazoquinolines generate macrophage microbicidal activity, a cDNA gene array analysis was undertaken to identify genes induced by S-28463. Out of 588 genes screened in this assay, only 13 genes were significantly induced by S-28463. Remarkably, virtually all of the induced genes are involved in macrophage activation and inflammatory response. This experimental approach defines the mechanism of action of this clinically relevant compound in the induction of microbicidal activity in macrophages and also potentially identifies novel genes associated with microbicidal activity in this cell type.

The organotypic culture of HPV-transformed keratinocytes: an effective in vitro model for the development of new immunotherapeutic approaches for mucosal (pre)neoplastic lesions

The purpose of this study is to develop a reliable in vitro human model to test new immunotherapeutic approaches for squamous cell carcinoma that develop on mucosal surfaces. The organotypic (raft) culture permits cells to proliferate and differentiate at an air-liquid interface on a dermal equivalent support. Normal keratinocytes stratify and fully differentiate in a manner similar to the normal squamous epithelial tissues, while human papillomavirus-immortalized and established squamous carcinoma cell lines exhibit dysplastic morphologies similar to (pre)neoplastic lesions seen in vivo. We have demonstrated the ability of these organotypic cultures to be manipulated by altering the epithelial stratification with cytokines (interferon-gamma and tumor necrosis factor-alpha) and by integrating activated lymphocytes or dendritic cells into the in vitro formed epithelial sheet. This model may provide a useful tool to investigate the factors contributing to the presence and function of immunocompetent cells within a neoplastic epithelium that develops on a mucosal surface.

Dermal dendritic cells in anogenital warty lesions unresponsive to an immune-response modifier

BACKGROUND

Human papilloma viruses (HPV) are responsible for a variety of proliferative epithelial lesions including anogenital condylomas. These lesions may regress during treatment with an immune-response modifier such as imiquimod. The release of specific cytokines from the monocyte-macrophage lineage induces a cascade of events abating the HPV replication.

METHOD

A total of 14 persistent warty anogenital lesions were excised 4 to 7 weeks after completing a 4-month imiquimod treatment. Another series of 25 untreated condylomas and 8 bowenoid papulosis served as controls. All examined lesions had been excised in otherwise healthy individuals with a normal immune status. Lesions were examined for the presence of Langerhans cells and subpopulations of the monocyte/macrophage/dendrocyte lineage using immunohistochemical detection of L1-protein, CD68, lysozyme and Factor-XIIIa. CD45R0-positive T lymphocytes were also identified. HPV capsid antigens and genotypes were searched for using immunohistochemistry and in situ hybridization, respectively.

RESULTS

The persistent although treated anogenital lesions were identified as 10 viral condylomas, 3 bowenoid papulosis and 1 basal cell carcinoma. The inflammatory cell densities and distributions were similar in the untreated and imiquimod-resistant condylomas with the exception of Factor XIIIa-positive dendrocytes. These dermal dendritic cells were slim and rare in all imiquimod-resistant lesions. In contrast, about two-thirds of the untreated condylomas were enriched in these cells.

CONCLUSION

As dermal dendritic cells play a role in the immune surveillance, their low densities in some lesions might be a key feature responsible for low cytokine local production and failure of imiquimod treatment. The combined apparent lack of Langerhans cell activation might suggest that both intraepidermal and intradermal compartments of antigen-presenting cells are affected in imiquimod-resistant lesions.

Natural T-helper immunity against human papillomavirus type 16 (HPV16) E7-derived peptide epitopes in patients with HPV16-positive cervical lesions: identification of 3 human leukocyte antigen class II-restricted epitopes

Tumor-specific T-helper (Th) immunity was found to play a pivotal role in the natural and vaccine-induced immune defense against tumors. Since the majority of cervical cancers express human papillomavirus type 16 (HPV16) E7 oncoprotein, it is important to investigate the Th response against this target antigen in detail. By means of PBMC cultures from HLA-typed healthy donors, we identified the central part of HPV16 E7 (E7(41-72)) as the major immunogenic region within this antigen. Furthermore, we mapped 3 distinct Th epitopes within this region (DR15/E7(50-62), DR3/E7(43-77), DQ2/E7(35-50)). In a parallel approach, employing IFN-gamma ELISPOT analysis, we detected Th immunity against HPV16 E7 in subjects with HPV16+ lesions. Several of these responses matched with the 3 Th epitopes defined in our study. A number of other HPV16+ subjects did not display any E7-specific type 1 cytokine-producing T-cell immunity, indicating failure of the immune response. Our combined data argue for more extensive as well as longitudinal analysis of HPV16-specific T-cell immunity using the ELISPOT assay described, as well as for HPV-specific vaccination of individuals with HPV+ lesions.