On the nature of the deep cellular disturbances in human-papilloma-virus infection of the squamous cervical epithelium

Transformation of the genital epithelial tract occurs early in California sea lion development

An unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging California sea lions stranded off the coast of California in the past two decades. No cases have been reported for sea lions in the relatively unpolluted Gulf of California. We investigated occurrence of genital epithelial transformation in 60 sea lions (n=57 pups and 3 adult females) from the Gulf of California and examined whether infection by a viral pathogen previously found to be associated with urogenital carcinoma accounted for such alterations. We also explored the contribution of MHC class II gene expression on transformation. Cellular alterations, such as squamous cell atypia (ASC), atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions were observed in 42% of the pups and in 67% of the adult females. Normal genital epithelium was more common in male than female pups. ASC was five times more likely to occur in older pups. Epithelial alterations were unrelated to infection by the potentially oncogenic otarine type I gammaherpesvirus (OtHV-1), but ASCUS was more common in pups with marked and severe inflammation. Expression of MHC class II DRB loci (Zaca DRB-D) by peripheral antigen-presenting leucocytes showed a slightly 'protective' effect for ASC. We propose that transformation of the California sea lion genital epithelium is relatively common in young animals, increases with age and is probably the result of infection by an unidentified pathogen. Expression of a specific MHC class II gene, suggestive of presentation of specific antigenic peptides to immune effectors, appears to lower the risk of transformation. Our study provides the first evidence that epithelial transformation of the California sea lion genital tract is relatively common, even from an early age, and raises questions regarding differences in sea lion cancer-detection and -repair success between geographical regions.

Human papillomavirus type 16 E1circumflexE4 contributes to multiple facets of the papillomavirus life cycle

The life cycle of human papillomaviruses (HPVs) is tightly linked to the differentiation program of the host's stratified epithelia that it infects. E1(circumflex)E4 is a viral protein that has been ascribed multiple biochemical properties of potential biological relevance to the viral life cycle. To identify the role(s) of the viral E1(circumflex)E4 protein in the HPV life cycle, we characterized the properties of HPV type 16 (HPV16) genomes harboring mutations in the E4 gene in NIKS cells, a spontaneously immortalized keratinocyte cell line that when grown in organotypic raft cultures supports the HPV life cycle. We learned that E1(circumflex)E4 contributes to the replication of the viral plasmid genome as a nuclear plasmid in basal cells, in which we also found E1(circumflex)E4 protein to be expressed at low levels. In the suprabasal compartment of organotypic raft cultures harboring E1(circumflex)E4 mutant HPV16 genomes there were alterations in the frequency of suprabasal cells supporting DNA synthesis, the levels of viral DNA amplification, and the degree to which the virus perturbs differentiation. Interestingly, the comparison of the phenotypes of various mutations in E4 indicated that the E1(circumflex)E4 protein-encoding requirements for these various processes differed. These data support the hypothesis that E1(circumflex)E4 is a multifunctional protein and that the different properties of E1(circumflex)E4 contribute to different processes in both the early and late stages of the virus life cycle.

New markers for cervical dysplasia to visualise the genomic chaos created by aberrant oncogenic papillomavirus infections

Extensive research over the past 20 years provided strong evidence that persistent infections with high risk type human papillomaviruses (HR-HPVs) cause cervical cancer. However, depending on their age, more than 20% of normal women are infected with these viruses and only very few develop clinically relevant dysplastic lesions or even cancer. During an acute HPV infection, expression of viral genes, in particular the viral E6 and E7 oncogenes is restricted to differentiated epithelial cells, which lost the capability to replicate their genomes and are therefore at no further risk for acquiring functionally relevant mutations upon genotoxic damage. High grade cervical dysplasia, however, is initiated by deregulated expression of viral oncogenes in replicating epithelial stem cells. Here, the E6-E7 gene products submerge control of the cell cycle and mitotic spindle pole formation through complex interactions with various cellular protein complexes and induce severe chromosomal instability. The detailed molecular analysis of these interactions allowed to define new biomarkers for dysplastic cervical cells. E7 for example induces increasing expression of the cyclin dependent kinase inhibitor p16(ink4a) in dysplastic cells. This can be used to identify dysplastic cells in histological slides, cytological smears or samples taken for biochemical analyses with an yet unmet fidelity. Detection of specific viral mRNAs derived from integrated HPV genomes in advanced precancers can be used to identify lesions with a particularly high risk for progression into invasive carcinomas (APOT assay). These new markers will result in a modified classification of cervical precancers and improved screening assays. Here, we review the basic concept and potential clinical applications of these new developments.

Human papillomavirus-associated oral epithelial dysplasia (koilocytic dysplasia): an entity of unknown biologic potential

Intraepithelial neoplasia of the female genital tract has long been associated with human papillomavirus infection. To date, there have been no previously published studies of oral dysplasia that have identified light microscopic features predictive of the presence of human papillomavirus. We identified a variant of oral epithelial dysplasia, koilocytic dysplasia, that exhibited light microscopic features suggestive of HPV infection. To determine if these microscopic features were specifically correlated with human papillomavirus infection, DNA in situ hybridization for human papillomavirus 6/11, 16/18, and 31/33/51 was performed on 31 lesions diagnosed histologically as koilocytic dysplasia. Seventeen matched control cases of conventional oral epithelial dysplasia were also analyzed for human papillomavirus. Human papillomavirus DNA was detected significantly more often (p < 0.001) in koilocytic dysplasia (80.6%) than conventional oral epithelial dysplasia (0.0%). Positive cases of koilocytic dysplasia contained either intermediate-risk (31/33/51) or high-risk (16/18) human papillomavirus types whether or not they contained low-risk human papillomavirus types (6/11). The histologic and clinical presentation of koilocytic dysplasia was unique. Lesions demonstrated koilocytes and other microscopic characteristics of human papillomavirus infection, as well as features of conventional epithelial dysplasia. A striking male predominance was noted, as was a relatively young average age of presentation (39.0 years). On the basis of our preliminary analysis, we conclude that oral koilocytic dysplasia represents a unique pathologic entity and that the presence of human papillomavirus can be predicted on light microscopy with at least 80% accuracy. The clinical significance and potential for malignant transformation of koilocytic dysplasia remain to be investigated.

Transmission of genital human papillomavirus infections is unlikely through the floor and seats of humid dwellings in countries of high-level hygiene

To evaluate the transmission of genital human papillomavirus (HPV) through the floor and seats of humid dwellings, samples were collected with a toothbrush from the floor and seat surfaces of humid dwellings; showers, saunas and dressing rooms. The survey included 3 bathing resorts, 1 indoor swimming pool, 2 schools and 2 private homes. Polymerase chain reaction (PCR) was used to amplify the human beta-globin gene and HPV DNA. The results for HPV DNA amplification were confirmed by Southern blot hybridization under low stringency using a probe mixture of HPV types 6, 16, 18 and 31. beta-globin could be amplified only from 3 sample taken from a dressing room of and indoor public swimming pool. No HPV DNA-positive samples were found. These results indicate that transmission of genital HPV infection via floor or seat surfaces in the above dwellings in general or family use is highly unlikely.

Epstein-Barr virus--a possible missing link in the initiation of cervical carcinogenesis?

Salient epidemiological and molecular biological features of Epstein-Barr virus (EBV) infection correlate well with the natural history of carcinoma of the cervix. It is therefore hypothesised that the incorporation of EBV into the genome of cervical epithelial cells at an early age (teens) could be an important early event in cervical carcinogenesis.

Underwear: contamination by human papillomaviruses

Genital human papillomavirus-related lesions occurring in 74 patients and cellular swab samples taken from their underwear were analyzed with a filter hybridization technique (ViraPap-ViraType, Life Technologies Inc., Gaithersburg, Md.) for human papillomavirus deoxyribonucleic acid. Human papillomavirus deoxyribonucleic acid was found in 54 of 74 (72%) lesional tissues and 13 of 74 (17%) swabs from the underwear. Recurrence rates in patients with and without positive underwear swabs were 61% and 29% (p less than 0.05), respectively.

Prediction of human papilloma virus antigen in cervical squamous epithelium by koilocyte nuclear morphology and "wart scores": confirmation by immunoperoxidase

Koilocytes (balloon cells) in cervical squamous epithelium can be distinguished by their nuclear morphology as members of two populations A and B. The proposition that population A was infected with human papilloma virus (HPV) and population B was not, was examined immunohistologically. A peroxidase-antiperoxidase technique using polyclonal HPV antibody failed to support the hypothesis and showed small fractions of both populations to be infected with the virus (A = 5 of 25; B = 2 of 19). Nuclear morphology alone is thus inadequate to distinguish infected from non-infected koilocytes, or balloon cells. When a number of well established histological changes in squamous epithelia infected with HPV were examined, graded, and summated to obtain a "wart score," however, a reasonably accurate prediction of HPV infection emerged.

An improved in situ DNA hybridization protocol for detection of human papillomavirus (HPV) DNA sequences in paraffin-embedded biopsies

In situ DNA hybridization is becoming rapidly an important technique for detection and typing of human papillomaviruses (HPV) in epithelial lesions, some of which (those due to HPV 16, 18 and 31) seem to possess an increased risk for progression into an invasive squamous cell carcinoma. An improved in situ DNA hybridization technique (Technique II) was described, and the results obtained in a series of cervical and penile HPV lesions were compared with those given by the in situ hybridization technique (Technique I) previously used in our laboratory. Special emphasis was made to increase the sensitivity with three basic alterations of the hybridization protocol; omission of the 0.2 N HCl wash, use of increased proteinase K concentration (from 50 micrograms/ml to 1 mg/ml), and elevated denaturation temperature (obtained by a heating block instead of an incubator). Poly-D-lysine as a slide-coating medium was replaced by Kodak Photo-Flo 200 to improve the attachment of the tissue sections on the slides. Identical HPV DNA types were discovered by the two hybridization techniques. The attachment of the tissue sections was equal on the slides coated with either poly-D-lysine or Kodak Photo-Flo 200, and the latter did not interfere with the sensitivity of in situ hybridization. The hybridization signals for HPV DNA were weak or moderate in 15/16 lesions with Technique I, but intense in 10/16 lesions with Technique II (P less than 0.001). Furthermore, the resolution of Technique II seemed to be superior to that of Technique I, while being capable of disclosing HPV DNA in the intermediate cell layers (P less than 0.001) and in basal/parabasal cell layers (P less than 0.025) of both the cervical and penile lesions. The discovery of HPV DNA in the parabasal cells provides important clues to the understanding of the biology of HPV infection in the squamous epithelium, and makes this improved in situ DNA hybridization technique invaluable in assessing the lesions, where low copy numbers of HPV are to be expected.

Immunophenotypes of lymphocytes in prospectively followed up human papillomavirus lesions of the cervix

From 1981 286 women were prospectively followed up for a mean (SD) of 16 (14) months for established infection with human papillomavirus (HPV) with or without coexistent cervical intraepithelial neoplasia (CIN). The in situ immunocompetent cell infiltrates in 263 cervical punch biopsy specimens from these women were phenotypically identified by the avidinbiotin peroxidase complex (ABC) technique using monoclonal antibodies Leu-10, OKT-3, OKT-4, and OKT-8. Leu-10+ B lymphocytes far outnumbered the OKT-3+ T lymphocytes in all types of HPV lesions (flat, inverted, and papillomatous condylomas of the cervix). The ratio of OKT-4+ to OKT-8+ (T helper to T suppressor cells) was slightly reduced in HPV lesions with more severe CIN and correlated positively with the intensity of the immunocompetent cell infiltrate. The ratio of OKT-4+ to OKT-8+ cells was highest in the 47 (28.8%) patients with HPV lesions that regressed during follow up, somewhat lower in the 85 (52.1%) with persistent lesions, and lowest in the 31 (19.1%) with lesions showing clinical progression. The results are discussed in terms of the proposed immune surveillance functions attributed to immunocompetent cells in situ according to the mucosal associated lymphatic tissue (MALT) concept. The conclusion drawn is that a dynamic balance between the immunoregulatory cells and their subtypes is a prerequisite for the proper handling of intracellular infections of the mucosa, including that with HPV.