Filaggrin expression in cutaneous and mucosal human papillomavirus induced lesions

Common filaggrin gene mutations and risk of cervical cancer

BACKGROUND

As carriers of filaggrin gene (FLG) mutations may have a compromised cervical mucosal barrier against human papillomavirus infection, our primary objective was to study their risk of cervical cancer.

METHODS

We genotyped 586 cervical cancer patients for the two most common FLG mutations, R501X and 2282del4, using blood from the Copenhagen Hospital Biobank, Denmark. Controls (n = 8050) were genotyped in previous population-based studies. Information on cervical cancer, mortality and emigration were obtained from national registers. Odds ratios (OR) were estimated by logistic regression with adjustment for age at blood sampling, and weighted by the genotype-specific inverse probability of death between diagnosis and sampling. Hazard ratios (HR) were estimated by Cox regression with time since diagnosis as underlying time, and with adjustment for age at diagnosis and stratification by cancer stage.

RESULTS

The primary results showed that FLG mutations were not associated with the risk of cervical cancer (6.3% of cases and 7.7% of controls were carriers; OR adjusted 0.81, 95% CI 0.57-1.14; OR adjusted+ weighted 0.96, 95% CI 0.58-1.57). Among cases, FLG mutations increased mortality due to cervical cancer (HR 4.55, 95% CI 1.70-12.2), however, the association was reduced after stratification by cancer stage (HR 2.53, 95% CI 0.84-7.59).

CONCLUSION

Carriage of FLG mutations was not associated with the risk of cervical cancer.

Immunohistochemical localization of filaggrin in benign, premalignant and malignant cervical tissue

Epithelial distribution of filaggrin, a histidine-rich protein related to squamous terminal differentiation, was investigated in 87 cervical biopsies using an avidin-biotin-peroxidase technique with a monoclonal anti-human filaggrin antibody (AKH1). Normal squamous cervical epithelium exhibited a positive homogeneous immunoperoxidase stain in the upper parabasal, intermediate and superficial cell layers. Similar findings were obtained in cervical condylomas, although full-thickness staining was observed in 35.7% of the cases (P < 0.001). Filaggrin expression in CIN was inversely related to the severity of the lesion (P < 0.001). An irregular staining pattern was present in most high-grade CIN. Filaggrin expression was closely connected to the degree of tumour differentiation (P < 0.05) in squamous cell carcinomas of the cervix. Abnormal filaggrin stainings identified a premalignant/malignant cervical squamous lesion with a positive predictive value of 92.3%. Non-squamous epithelia showed lack of filaggrin expression. Filaggrin may therefore be considered a marker of squamous differentiation in both the normal and pathological human uterine cervix.

Expression of annexin I in freshly isolated human epidermal cells and in cultured keratinocytes

Annexin I belongs to a newly characterized family of intracellular proteins involved in the regulation of the production of inflammatory lipid mediators such as prostaglandins and leucotrienes. Annexin I (named p35, lipocortin I or calpactin II) was initially described as a protein inducible by glucocorticoids. In the skin, the role of annexins has still not been elucidated. In the study reported here we investigated the expression of annexin I both in freshly isolated epidermal cells and in cultured keratinocytes using immunofluorescence, FACS analysis and immunoblotting techniques. Using epidermal cells freshly isolated from normal skin, annexin I was detected by double immunostaining mainly in basal and suprabasal keratinocytes. Langerhans cells isolated from Ficoll gradient were faintly stained compared with keratinocytes. Annexin I was also highly expressed in keratinocytes maintained in culture in a serum-free medium without hydrocortisone. By confocal microscopy, annexin I was shown to be mainly localized in the cytoplasm of the cells. The protein was characterized by Western blot and immunoprecipitation as a 35-kDa protein in freshly isolated epidermal cells and cultured keratinocytes. Results from in vivo studies confirmed the presence of annexin I in the basal and suprabasal layers of normal human skin with modified reactivity patterns in hyperproliferative lesions.

Langerhans cells and epithelial cell modifications in cervical intraepithelial neoplasia: correlation with human papillomavirus infection

The study of a series of 18 cervical intraepithelial neoplasia (CIN) grade II and III was aimed at determining the distribution and phenotype of immunocompetent cells (Langerhans cells, T and NK cells) and the alteration in the expression of EGF receptors and beta 2-microglobulin in correlation with human papillomavirus (HPV) infection (viral antigen and DNA typing with biotinylated probes). These lesions were characterized by a reduced number of Langerhans cells and a dense infiltrate. HPV infection did not induce HLA-DR expression in the infected epithelial cells. We observed an enhanced expression of epidermal growth factor (EGF) receptors by epithelial cells and a reduced beta 2-microglobulin reactivity by both epithelial and immunocompetent cells. Most of CIN showed foci of infected cells. No significant differences were observed in immunological markers of CIN harboring benign HPV 6/11 DNA or oncogenic HPV 16/18 DNA. Viral antigen was not detected in these lesions. These changes in the epithelial cells of CIN and their microenvironment associated to the lack of HLA-DR expression in the infected cells hamper the squamous epithelial cells to function as antigen presenting cells. This may facilitate a decrease in the immunological surveillance and may contribute to the severity of such lesions.

Human papillomavirus infection and filaggrin expression in paraffin-embedded biopsy specimens of extragenital Bowen's disease and genital bowenoid papulosis

Cutaneous Bowen's disease (BD) and genital bowenoid papulosis (BP) are considered as precancerous or cancerous lesions that are sometimes infected with human papillomavirus (HPV). We studied retrospectively paraffin-embedded sections of 11 samples of cutaneous BD and 6 samples of genital BP from the general population for HPV infection and filaggrin expression. Using in situ hybridization with biotinylated probes of HPV types 1, 2, 5, 6, 11, 16, and 18, under stringent and/or non-stringent conditions and a streptavidin-alkaline-phosphatase complex for hybrid detection, HPV DNA was detected in 6/17 cases (5 BD and 1 BP). Positive nuclei were located in intermediate or upper epithelial cell layers. HPV 16 was found in 2 cases of BD but associated either with HPV 2 or 18. Three additional lesions reacted only under non-stringent conditions; HPV could not be typed with the probes used. The positive case of BP reacted with the four probe types 1, 2, 16, 18 and was negative with HPV 6 or 11. Viral antigen was not detected by indirect immunofluorescence with a rabbit antiserum directed to group-specific viral capsid antigen. Differentiation disorders were observed in the intermediate and upper cell layers of these specimens, as shown by a reduced expression of filaggrin/profilaggrin, a marker of terminal differentiation, in extragenital BD (7/11 cases), and an increased expression in genital BP (4/5 cases) although viral DNA was not always detectable. This study shows that in situ hybridization is a valuable technique for HPV DNA detection and its typing in BD and BP lesions on deparaffinized sections. The positive nuclei were located in the cell layers that exhibited abnormal expression of differentiation. There is no relation between the HPV infecting type and the filaggrin expression.