Natural killer cells in cervical intraepithelial neoplasia and human papillomavirus infection

NK Cell Regulation in Cervical Cancer and Strategies for Immunotherapy

Cervical cancer is one of the most prevalent gynaecological malignancies worldwide and is related to human papillomavirus (HPV) infection, viral persistence, progression, and invasion. Therefore, the immune response is linked to HPV status. Natural killer (NK) cells play a central role against virus-infected cells and tumours through a delicate balance between activating and inhibitory receptors and secretion of cytokines and chemokines. These cells also play a crucial role in tumour immunosurveillance. For these reasons, there is growing interest in harnessing NK cells as an immunotherapy for cervical cancer. These studies are diverse and include many strategies such as transferring activated autologous or allogeneic NK cells, improving the activation and cytolytic activity of NK cells using cytokines or analogues and modifying chimeric antigen receptors to increase specificity and targeting NK cells. However, research regarding the application of NK cells in immunotherapy is limited. This article focuses on recent discoveries about using NK cells to prevent and treat cervical cancer and the possibility of cellular immunotherapy becoming one of the best strategies to exploit the immune system to fight tumours.

Local Impairment of Immunoreactivity in Hiv-infected Women with Hpv-related Squamous Intraepithelial Lesions of the Cervix

Aims and background

The aim of this study was to compare the local immune response in two groups of patients with high-grade cervical intraepithelial squamous lesions (SIL): one with HIV infection and the other with HPV infection alone.

Materials and methods

16 conization specimens (8 from HIV-infected and 8 from non-HIV-infected patients) of HPV-related, high-grade SIL were selected. The specimens from non-HIV patients were considered as controls. The total number of Langerhans cells, CD4 and CD8 cells present in 10 field areas (3.120 mm2) was recorded in each case. In HIV patients CD4 and CD8 peripheral counts were performed immediately before surgery.

Results

The CD4/CD8 ratio never exceeded 0.71, whereas the lowest ratio in controls was 0.81: this difference was statistically significant (P=0.0009). The mean number of Langerhans cells was markedly reduced in the high-grade SILs in the HIV patients in comparison with controls (P=0.001). The number of CD4 cells and the CD4/CD8 ratio correlated with the peripheral CD4 count (P=0.001 and 0.02).

Conclusions

In our study a marked local impairment of cervical immunoreactivity was observed, which may play a major role in the progression of these lesions in HIV-infected women.

Humoral Immune Response Against Human Papillomavirus as Source of Biomarkers for the Prediction and Detection of Cervical Cancer

Cervical cancer (CC) is one of the main causes of death among women of reproductive age. Although there are different tests, the disease tends to be diagnosed at late stages. In recent years, the use of complementary tests or sequential diagnostic tests has been implemented. Nevertheless, the results are variable and not conclusive; therefore, more studies for improving the usefulness of these tests in diagnostics are necessary. The human papillomavirus (HPV) infection has been associated with both benign and malignant proliferation of skin and mucosal tissues. Furthermore, some HPV types have been classified as high risk due to their potential to cause cancer, and HPV16 is most frequently associated with this disease. Although between 70% and 80% of precancerous lesions are eliminated by the host's immune system, there is no available test to distinguish between regressive lesions from those that could progress to CC. An HPV infection generates a humoral immune response against L1 and L2 capsid proteins, which can be protective and a response against early proteins. The latter is not a protective response, but these antibodies can be used as markers to determine the stage of the infection and/or the stage of the cervical lesion. Up to now, the humoral immune response resulting from the HPV infection has been used to study the biology of the virus and the efficacy of the HPV vaccines. Although there are no conclusive results regarding the use of these antibodies for diagnosis, we hereby review the actual panorama of the antibody response against the HPV proteins during the development of the disease as well as their possible use as biomarkers for the progression of cervical lesions and of CC.

HPV vaccine stimulates cytotoxic activity of killer dendritic cells and natural killer cells against HPV-positive tumour cells

Cervarix™ is approved as a preventive vaccine against infection with the human papillomavirus (HPV) strains 16 and 18, which are causally related to the development of cervical cancer. We are the first to investigate in vitro the effects of this HPV vaccine on interleukin (IL)-15 dendritic cells (DC) as proxy of a naturally occurring subset of blood DC, and natural killer (NK) cells, two innate immune cell types that play an important role in antitumour immunity. Our results show that exposure of IL-15 DC to the HPV vaccine results in increased expression of phenotypic maturation markers, pro-inflammatory cytokine production and cytotoxic activity against HPV-positive tumour cells. These effects are mediated by the vaccine adjuvant, partly through Toll-like receptor 4 activation. Next, we demonstrate that vaccine-exposed IL-15 DC in turn induce phenotypic activation of NK cells, resulting in a synergistic cytotoxic action against HPV-infected tumour cells. Our study thus identifies a novel mode of action of the HPV vaccine in boosting innate immunity, including killing of HPV-infected cells by DC and NK cells.

Local expression of TAP-1 and MHC-I molecules and their relationship in condyloma acuminatum

BACKGROUND

Condyloma acuminatum (CA), caused by human papillomavirus (HPV), is characterized by a variable clinical course that can include significant morbidity, frequent disease recurrence and occasional oncogenicity. Effective CD8+ T-cell-mediated clearance of HPV-infected cells may be defective in patients with CA, leading to recurrent disease and failure to suppress latent HPV reactivation. The pathogenesis responsible for CA and the persistence of latent HPV infection remain unknown.

OBJECTIVE

To determine whether expression of transporters associated with antigen processing 1 (TAP-1) and the major histocompatibility complex class I (MHC-I) is involved in HPV immune escape.

METHODS

In this present study, we compared 31 CA lesions with 30 normal prepuces by immunohistochemistry and reverse transcription PCR for their expressions of TAP-1 and MHC-I.

RESULTS

Expressions of TAP-1 and MHC-I were significantly reduced in CA tissue biopsies compared with normal prepuces. There was a statistically significant positive correlation between expressions of TAP-1 and MHC-I in CA lesions. Furthermore, we found that TAP-1 mRNA was significantly reduced in CA lesions compared with those in normal prepuces.

CONCLUSION

These results suggest that HPV may evade immune recognition by downregulating MHC-I cell surface expression via decreased TAP-1 levels.

Oncogenicity of human papillomavirus- or adenovirus-transformed cells correlates with resistance to lysis by natural killer cells

The reasons for the dissimilar oncogenicities of human adenoviruses and human papillomaviruses (HPV) in humans are unknown but may relate to differences in the capacities of the E1A and E7 proteins to target cells for rejection by the host natural killer (NK) cell response. As one test of this hypothesis, we compared the abilities of E1A- and E7-expressing human fibroblastic or keratinocyte-derived human cells to be selectively killed by either unstimulated or interferon (IFN)-activated NK cells. Cells expressing the E1A oncoprotein were selectively killed by unstimulated NK cells, while the same parental cells but expressing the HPV type 16 (HPV-16) or HPV-18 E7 oncoprotein were resistant to NK cell lysis. The ability of IFN-activated NK cells to selectively kill virally transformed cells depends on IFN's ability to induce resistance to NK cell lysis in normal (i.e., non-viral oncogene-expressing) but not virally transformed cells. E1A blocked IFN's induction of cytolytic resistance, resulting in the selective lysis of adenovirus-transformed cells by IFN-activated NK cells. The extent of IFN-induced NK cell killing of E1A-expressing cells was proportional to the level of E1A expression and correlated with the ability of E1A to block IFN-stimulated gene expression in target cells. In contrast, E7 blocked neither IFN-stimulated gene expression nor IFN's induction of cytolytic resistance, thereby precluding the selective lysis of HPV-transformed cells by IFN-activated NK cells. In conclusion, E1A expression marks cells for destruction by the host NK cell response, whereas the E7 oncoprotein lacks this activity.

Psychoneuroimmunological aspects of disease progression among women with human papillomavirus-associated cervical dysplasia and human immunodeficiency virus type 1 co-infection

OBJECTIVE

Psychosocial associations have been observed with level of cervical dysplasia or "pre-cancer" and invasive cervical cancer [related to human papillomavirus (HPV) infection]. Psychoneuroimmunological relationships have been observed in human immunodeficiency virus type 1 (HIV-1) infection, which is being described in an increasing number of women. Our objective was to review these relationships regarding effects that might be expected in HIV-1 and HPV co-infected women.

METHOD

This review was based on a Medline literature search supplemented by a manual search of selected journals unrepresented in that database.

RESULTS

Relationships of psychosocial factors and level of cervical dysplasia were similarly observed with reference to immunological and health status in asymptomatic and early symptomatic HIV-1 infected homosexual men, suggesting that a potentiating effect may occur in HIV-1 and HPV co-infected women. Consistency of relationships across studies appeared to be enhanced by the use of a biopsychosocial model integrating the effects of life stressors, social support and coping style as well as psychiatric disorders.

CONCLUSIONS

Research is indicated on the relationships between psychosocial factors, immunological status and clinical health status in this group of women. Because of the high prevalence of psychosocial risk factors for chronic psychological distress in these women and the known immunological and health status decrements occurring with progression of these two infections, a clinical screening program based on the biopsychosocial model is recommended as a means of secondary prevention. If effective in generating treatment referrals, such a program would likely improve quality of life and could aid in the determination of relationships with immunological and health status as well.

Immunological modulation of lymphocyte subpopulation in cervical cancer tissue by sizofiran and OK-432

The intimate correlation between marked lymphocyte infiltration in the cancer tissue and the superior clinical prognosis has been reported in human cancers. Sizofiran (SPG), a polysaccharide consisting of beta-1,3-D-glucopyranosyl linkage with beta-1,6-D-glucopyranosyl branches, or OK-432, a heat- and penicillin-treated, lyophilized preparation of the Su strain of Streptococcus pyogenes of human origin, was administered intratumorally to nine patients with advanced uterine cervical carcinoma before radical hysterectomy to assess their immunological modulating properties to tumor-infiltrating lymphocyte subpopulations immunohistochemically. The degree of infiltration of CD3- and CD5-positive cells increased moderately or markedly in the stroma surrounding the lesion in both SPG group and OK-432 group, as well as that of CD4- and CD8-positive cells, from that before administration. The density of infiltration of CD3-positive, CD4-positive, and CD8-positive cells in the lesion increased slightly or moderately in both groups after administration. As for CD16-positive cell infiltration, both SPG and OK-432 increased its degree in the stroma lining the lesion while SPG alone augmented its degree in the lesion. This augmentation of lymphocyte infiltration in situ induced by intratumoral administration of SPG and OK-432 is expected to lead to a favorable prognosis of patients with cervical cancer.

Life stressors and coping style are associated with immune measures in HIV-1 infection--a preliminary report

OBJECTIVE

Life stressors and coping style have been associated with alterations in cellular immunity similar to those seen in HIV-1 infection. The interval between infection with HIV-1 and the development of AIDS is lengthy and highly variable. This pilot study investigated whether life stressors and coping style may account for a portion of this variation.

METHOD

A sample of eleven asymptomatic HIV-1 seropositive homosexual male volunteers responding to a local advertisement was assessed on life stressors, coping style and cellular phenotypic and functional immune measures--T4 "helper" cell/T8 "suppressor" cell ratio, T4 cell count, total lymphocyte count, and natural killer cell cytotoxicity.

RESULTS

Significant associations were observed for both major life stressor impact over the previous year and passive coping style use with the total lymphocyte count; higher life stressor impact and passive coping style use were associated with lower total lymphocyte counts. Similarly, a trend in the same direction was found for the relationship of these two measures with the count of T4 cells, which are directly infected and killed by HIV-1.

CONCLUSIONS

It is well documented that decrements in T4 cell and total lymphocyte counts are powerful predictors of subsequent clinical progression to AIDS. These preliminary findings suggest that life stressors and coping style may also be predictors of the development of AIDS.

Morphometric analysis and identification of infiltrating leucocytes in regressing and progressing Shope rabbit papillomas

Spontaneous regressions of papillomavirus lesions frequently occur in both human and animal infections. The mechanism by which this occurs is currently unknown. Mononuclear infiltrates are found in regressing human and rabbit papillomas. To assess the potential functional role of these infiltrates in regression, we have characterized and quantitated the cell types present in regressing rabbit lesions. Forty New Zealand white rabbits were inoculated with cottontail rabbit papillomavirus (CRPV) at 2 sites on the dorsal skin. All tumors on 6 rabbits markedly decreased in volume within 6 to 8 weeks of inoculation. Tumors on 4 of these 6 regressor rabbits were studied by immunohistochemistry. Regressor papillomas had conspicuous leucocytic infiltrates, most concentrated at the epithelial basement membrane, and often obliterating the basal cells of the germinal layer. Infiltrating leucocytes were also concentrated in the subjacent dermis immediately beneath the basement membrane. The infiltrates gradually lessened at increased depths in the dermis. In contrast, progressor papillomas contained fewer leucocytes, which were randomly distributed in the dermis. The phenotype of the infiltrating leucocytes was examined in 4 regressing and 12 progressing papillomas. In regressing papillomas, infiltrating leucocytes were predominantly T cells (68.0%), with relatively few B cells (7.4%). Progressing papilloma dermis contained fewer T cells and B cells than regressing papillomas. Most of the infiltrating T cells in regressing papillomas were labelled with a rabbit MHC-class-II-specific monoclonal antibody (MAb) (2C4), in contrast to only a small number in progressing papillomas. In addition to the leucocytic infiltrates, keratinocytes in regressing, but not in progressing, papillomas, frequently exhibited strong 2C4 staining. These results demonstrate that infiltration with T cells expressing rabbit class II is characteristic of regressing Shope papillomas and strengthens the assertion that cell-mediated immunity is the mechanism of Shope papilloma regression.

Immunocytochemical characterization of large granular lymphocytes in normal cervix and HPV associated disease

A quantitative immunocytochemical study of large granular lymphocytes (LGLs) in the normal cervix and in human papillomavirus (HPV) associated disease was performed using a panel of monoclonal antibodies which included those for LGL surface markers CD56, CD16, and CD57. Only CD56-positive cells were found within the ectocervical epithelium and these cells increased in number in cervical intraepithelial neoplasia (CIN) in comparison with normal cervix. Examination of serial sections and double labelling suggests that these cells are CD3+, CD8+, CD56+, CD16+. The observed increase in number of this subset was not associated specifically with HPV infection but was related to CIN. Lymphocytes expressing all three LGL markers were found in the stroma and CD16(+)-positive cells clustered around endocervical glands with occasional cells extending into the endocervical epithelium. These results indicate that a small subset of LGLs which express T-cell markers is increased in number in CIN. Cells expressing classical NK markers are restricted to the stroma and are not found within the ectocervical epithelium.

An immunohistological study of spontaneous regression of condylomata acuminata

An immunohistological study of four men whose perianal warts were undergoing spontaneous regression was undertaken, and the results compared with those obtained from non-regressing condylomata from six men. CD4+ and CD8+ cells were noted in the stroma of each wart, but there was no clear difference in the density of the infiltrate between regressing and non-regressing warts. Natural killer cells (CD16+ and CD57+) were only noted in the stroma and epidermis of regressing warts. Possible immunological mechanisms of regression of condylomata acuminata are discussed.

A histological and immunohistological study of cervical intraepithelial neoplasia in relation to recurrence after local treatment

A retrospective histological study was performed on 23 patients who had presented with recurrent cervical intraepithelial neoplasia (CIN) 18 months or more after apparently adequate local destructive treatment and a comparable control group of 23 patients who had no recurrence at 18 months. All recurrences were in women with CIN 3. Detailed examination of pretreatment biopsies showed that there were significant differences in both the extent of crypt involvement (P less than 0.01) and maximum depth of CIN (P less than 0.01) between the recurrent groups and the comparison group of women without recurrence. There was also a significant difference in mitotic count between the two groups (P less than 0.01). Immunocytochemical staining for Langerhans' cells or human papilloma virus common antigen showed no significant difference between the two groups. A mitotic count of 35 per ten high-power fields or a depth of crypt involvement greater than 1.7 mm in the pretreatment biopsy was invariably associated with recurrence and identified 13/22 (59%) cases of recurrent disease. The histological reporting of these features may be of value in predicting a group of women at high risk of recurrence of CIN after local treatment.

Effect of cigarette smoking on cervical epithelial immunity: a mechanism for neoplastic change?

Langerhans' cells in cervical epithelium in colposcopic biopsy specimens were identified by immunocytochemical staining for S100 protein and T6 (CD1) antigen, and their density was quantified. Possible cofactors for the development of cervical neoplasia were examined for any effect on the cell counts per unit area. Current cigarette smoking was associated with a significant decrease in the Langerhans' cell population in both normal epithelium and lesions due to cervical intraepithelial neoplasia. Ex-smokers tended to have cell counts between those of smokers and non-smokers. There was a dose-response relation between number of cigarettes smoked daily and effect on cell counts. These findings of a local immunological effect of smoking on cervical epithelium may explain the means by which cigarette smoking contributes to the development of cervical neoplasia.