HLA class II allele control of HPV load in carcinomain situ of the cervix uteri

Association of two genomic variants with HPV type-specific risk of cervical cancer

PROBLEM

Human papillomavirus infection is integral to developing invasive cervical cancer in the majority of patients. In a recent genome-wide association study, rs9357152 and rs4243652 have been associated with seropositivity for HPV16 or HPV18, respectively. It is unknown whether these variants also associate with cervical cancer triggered by either HPV16 or HPV18.

METHODS

We investigate whether the two HPV susceptibility variants show association with type-specific cervical cancer in a genetic case-control study with cases stratified by HPV16 or HPV18, respectively. We further tested whether rs9357152 modulates gene expression of any of 36 genes at the human leukocyte antigen locus in 256 cervical tissues.

RESULTS

rs9357152 was associated with invasive HPV16-positive cervical cancer (OR 1.33, 95%CI 1.03-1.70, p = 0.03), and rs4243652 was associated with HPV18-positive adenocarcinomas (OR 2.96, 95%CI 1.18-7.41, p = 0.02). These associations remained borderline significant after testing against different sets of controls. rs9357152 was found to be an eQTL for HLA-DRB1 in HPV-positive cervical tissues (pANOVA = 0.0009), with the risk allele lowering mRNA levels.

CONCLUSIONS

We find evidence that HPV seropositivity variants at chromosome 6 and 14 may modulate type-specific cervical cancer risk. rs9357152 may exert its effect through regulating HLA-DRB1 induction in the presence of HPV. In regard of multiple testing, these results need to be confirmed in larger studies.

Genetic polymorphisms in Guillain-Barré Syndrome: A field synopsis and systematic meta-analysis

OBJECTIVE

Guillain-Barré Syndrome (GBS) is considered to be a complex immune-mediated neuropathy. In the past few years, numerous studies were performed to detect the association between genetic polymorphisms and GBS risk. However, the findings of these studies were controversial. Thus, we conducted this field synopsis and systematic meta-analysis for further evaluating the possible associations between all available genetic polymorphisms and GBS susceptibility.

METHODS

Relevant studies focusing on the association between all genetic polymorphisms and GBS risk were obtained by a comprehensive literature search. The pooled odds ratios (ORs) as well as 95% confidence intervals (CIs) were used for assessing the strength of association. Subgroup analyses stratified by ethnicity and GBS subtype were further performed. Moreover, sensitive analysis and publication bias were conducted for evaluating the reliability of the results.

RESULTS

Among the initial identified 333 articles, 41 articles reporting on 220 genetic polymorphisms were extracted for conducting this systematic review. Then, we performed 95 primary and 94 subgroup meta-analyses for 59 variants with at least three independent studies available. The results showed significant association between four variants (FcγR IIA rs1801274, TNF-α rs1800629, HLA DRB1*0401 and HLA DRB1*1301) and GBS susceptibility. In the subgroup analysis, three (TNF-α rs1800629, TNF-α rs1800630 and TLR4 rs4986790) and two (FcγR IIA rs1801274, HLA DRB1*14) variants showed association with increased GBS risk in Asian and Caucasian population, respectively. Also, TNF-α rs1800629 was significant associated with AMAN subtypes of GBS. Furthermore, sensitivity analysis, funnel plots and Egger's test displayed robust results, except for FcγR IIA rs1801274. Additionally, for 161 variants with less than three studies, 17 genetic variants have been found to be significantly related with GBS risk in our systematic review.

INTERPRETATION

In our study, we assessed the association between all available genetic polymorphisms and GBS susceptibility. We hope our findings would be helpful for identifying novel genetic biomarkers and potential therapeutic targets for GBS.

Investigation of Cervical Tumor Biopsies for Chromosomal Loss of Heterozygosity (LOH) and Microsatellite Instability (MSI) at the HLA II Locus in HIV-1/HPV Co-infected Women

Background: A subgroup of women who are co-infected with human immunodeficiency virus type 1 (HIV-1) and human papillomavirus (HPV) progress rapidly to cervical disease regardless of high CD4 counts. Chromosomal loss of heterozygosity (LOH) and microsatellite instability (MSI) are early frequent genetic alterations occurring in solid tumors. Loss of an allele or part of a chromosome can have multiple functional effects on immune response genes, oncogenes, DNA damage-repair genes, and tumor-suppressor genes. To characterize the genetic alterations that may influence rapid tumor progression in some HIV-1-positive women, the extent of LOH and MSI at the HLA II locus on chromosome 6p in cervical tumor biopsy DNA samples with regard to HIV-1/HPV co-infection in South African women was investigated.

Methods: A total of 164 women with cervical disease were recruited for this study, of which 74 were HIV-1-positive and 90 were HIV-1-seronegative. DNA from cervical tumors and matched buccal swabs were used for analyses. Six fluorescently-labeled oligonucleotide primer pairs in a multiplex PCR amplification were used to study LOH and MSI. Pearson chi-squared test for homogeneity of proportions using an exact p value, a two-proportion Z-score test, ROC curves and a logistic regression model were used for statistical analyses. All p-values were corrected for false discovery rate (FDR) using the Benjamini-Hochberg test and the adjusted p-values (q-values) were reported. All tests were significant when both p and q < 0.05.

Results: Tumor DNA from HIV-1/HPV co-infected women demonstrated a higher frequency of LOH/MSI at the HLA II locus on chromosome 6p21.21 than tumor DNA from HIV-1-seronegative women (D6S2447, 74.2 vs. 42.6%; p = 0.001, q = 0.003), D6S2881 at 6p21.31 (78.3 vs. 42.9%; p = 0.002, q = 0.004), D6S2666 at 6p21.32 (79 vs. 57.1%; p = 0.035, q = 0.052), and D6S2746, at 6p21.33 (64.3 vs. 29.4%; p < 0.001, q < 0.001), respectively.

Conclusions: HPV infection alone can induce LOH/MSI at the HLA II locus in cervical tumor DNA, whereas HIV-1 co-infection exacerbates it, suggesting that this may accelerate cervical disease progression in a subgroup of HIV-1-positive women.

Genetic susceptibility to cervical squamous cell carcinoma is associated with HLA-DPB1 polymorphisms in Taiwanese women

Cervical cancer is a multifactorial disease, and increasing evidence suggests that host immunogenetic background may contribute to its pathogenesis. Genetic variations in human leukocyte antigen (HLA) genes may alter the efficiency of immune response to human papillomavirus (HPV) antigens and have been implicated in the risk of cervical cancer. We investigated whether polymorphisms in the HLA-DPB1 gene were associated with cervical cancer risk in a Taiwanese population. HLA-DPB1 alleles and +550 G/A polymorphism were genotyped in a case-control study of 473 women with cervical squamous cell carcinoma (CSCC) and 676 healthy controls. The presence and genotypes of HPV in CSCC were determined. We found that the DPB1*05:01 and +550 A alleles were associated with decreased and increased risk of CSCC, respectively [odds ratio (OR) = 0.72, Pc = 0.001; OR = 1.25, Pc = 0.03]. In subgroup analysis based on HPV type 16 positivity, significant associations were shown in the DPB1*05:01 and *13:01 alleles (OR = 0.65, Pc = 0.0007; OR = 1.83, Pc = 0.004). Furthermore, the DPB1*05:01-G and *13:01-G haplotypes conferred decreased and increased risk of both CSCC and HPV-16 positive CSCC women, respectively (OR = 0.72, Pc = 0.0009; OR = 0.63, Pc = 0.0004 for DPB1*05:01-G; OR = 1.55, Pc = 0.03; OR = 1.84, Pc = 0.004 for DPB1*13:01-G). A risk haplotype DPB1*02:01-A was also observed in the HPV-16 positive CSCC women (OR = 1.51, Pc = 0.05). These findings suggest that HLA-DPB1 gene is involved in the CSCC development.

Genetic variants in HLA-DP/DQ contribute to risk of cervical cancer: a two-stage study in Chinese women

OBJECTIVE

Human leukocyte antigens (HLA) play an important role in presenting virus antigens to immune cells that are responsible for the clearance of virus-infected cells and tumor cells. Herein, we evaluated whether genetic variants of HLA-DP and HLA-DQ are associated with cervical cancer risk.

METHODS

We genotyped four single nucleotide polymorphisms (SNPs) in HLA-DP (rs3077 and rs9277535) and HLA-DQ (rs2856718 and rs7453920) in a two-stage case-control study with a total of 2317 cervical cancer cases and 2109 cancer-free controls using TaqMan allelic discrimination assay.

RESULTS

We found consistently significant associations of HLA-DP rs3077 and rs9277535 with increased risks of cervical cancer (dominant genetic model: adjusted OR=1.51, 95% CI=1.32-1.71 for rs3077; adjusted OR=1.29, 95% CI=1.12-1.49 for rs9277535). When combining the effects of HLA-DP rs3077 and rs9277535, subjects carrying "≥1" variant alleles had a 1.55-fold increased risk of cervical cancer (95% CI=1.32-1.81), compared with those carrying "0" variant allele. And cervical cancer risk significantly increased with the increasing number of variant alleles of the two SNPs in a dose-dependent manner (P for trend=4.33×10(-10)). However, there were no significant associations for HLA-DQ rs2856718 and rs7453920 in our population.

CONCLUSIONS

These findings indicate that HLA-DP rs3077 and rs9277535 were candidate susceptibility markers for cervical cancer in Chinese females. Further validation studies with different ethnic background, biological function analyses and especially HPV typing together were needed.

A comprehensive review on host genetic susceptibility to human papillomavirus infection and progression to cervical cancer

Cervical cancer is the second most common cancer in women worldwide. This is caused by oncogenic types of human papillomavirus (HPV) infection. Although large numbers of young sexually active women get HPV-infected, only a small fraction develop cervical cancer. This points to different co-factors for regression of HPV infection or progression to cervical cancer. Host genetic factors play an important role in the outcome of such complex or multifactor diseases such as cervical cancer and are also known to regulate the rate of disease progression. The aim of this review is to compile the advances in the field of host genetics of cervical cancer. MEDLINE database was searched using the terms, ‘HPV’, ‘cervical’, ‘CIN’, ‘polymorphism(s)’, ‘cervical’+ *the name of the gene* and ‘HPV’+ *the name of the gene*. This review focuses on the major host genes reported to affect the progression to cervical cancer in HPV infected individuals.

Association between human leukocyte antigen class II alleles and human papillomavirus-mediated cervical cancer in Indian women

We investigated the association of human leukocyte antigen (HLA) II (DRB1 and DQB1) alleles with susceptibility to human papillomavirus (HPV)-associated cervical precancer and cancer cases in a hospital-based case-control study in a northern Indian population. A total of 202 subjects, including 100 patients comprising 31 cervical precancer (cervical intraepithelial neoplasia [CIN] 2/3) and 69 invasive cervical cancer cases, and 102 healthy controls participated in the study. Both patients and controls were screened for HPV infection using a polymerase chain reaction (PCR-based approach. Low-resolution PCR-sequence specific priming (PCR-SSP) was used to genotype HLA II (DRB1 and DQB1). Our results demonstrate that the DRB1*15 allele/DRB1*15-DQB1*06 haplotype may have a predisposition for HPV infection (p(c) < 0.05) or cervical cancer/precancer (p(c) < 0.05) development, whereas the DRB1*04 allele/DRB1*04-DQB1*03 haplotype might exhibit susceptibility to cervical precancerous lesions (p(c) < 0.05). The DRB1*13 allele/DRB1*13-DQB1*06 haplotype was strongly protective against risk to HPV infection (p(c) < 0.002) as well as cervical cancer (p(c) 0.01). Therefore, we have demonstrated that HLA DR-DQ polymorphisms are involved in genetic susceptibility to cervical cancer or HPV infection in a northern Indian population.

Interaction between polymorphisms of the human leukocyte antigen and HPV-16 variants on the risk of invasive cervical cancer

Background

Persistent infection with oncogenic types of human papillomavirus (HPV) is the major risk factor for invasive cervical cancer (ICC), and non-European variants of HPV-16 are associated with an increased risk of persistence and ICC. HLA class II polymorphisms are also associated with genetic susceptibility to ICC. Our aim is to verify if these associations are influenced by HPV-16 variability.

Methods

We characterized HPV-16 variants by PCR in 107 ICC cases, which were typed for HLA-DQA1, DRB1 and DQB1 genes and compared to 257 controls. We measured the magnitude of associations by logistic regression analysis.

Results

European (E), Asian-American (AA) and African (Af) variants were identified. Here we show that inverse association between DQB1*05 (adjusted odds ratio [OR] = 0.66; 95% confidence interval [CI]: 0.39–1.12]) and HPV-16 positive ICC in our previous report was mostly attributable to AA variant carriers (OR = 0.27; 95%CI: 0.10–0.75). We observed similar proportions of HLA DRB1*1302 carriers in E-P positive cases and controls, but interestingly, this allele was not found in AA cases (p = 0.03, Fisher exact test). A positive association with DRB1*15 was observed in both groups of women harboring either E (OR = 2.99; 95% CI: 1.13–7.86) or AA variants (OR = 2.34; 95% CI: 1.00–5.46). There was an inverse association between DRB1*04 and ICC among women with HPV-16 carrying the 350T [83L] single nucleotide polymorphism in the E6 gene (OR = 0.27; 95% CI: 0.08–0.96). An inverse association between DQB1*05 and cases carrying 350G (83V) variants was also found (OR = 0.37; 95% CI: 0.15–0.89).

Conclusion

Our results suggest that the association between HLA polymorphism and risk of ICC might be influenced by the distribution of HPV-16 variants.

Immune concept of human papillomaviruses and related antigens in local cancer milieu of human cervical neoplasia

It is presently the right time for clarifying human papillomavirus (HPV)-associated cellular immunity and clinical implications before global HPV vaccination programs begin. Infection with oncogenic HPV associates with the progression of cervical neoplasia. Both cellular and humoral immune responses are essential for the clearance of HPV-associated cervical lesions. There is increasing evidence that the immune system plays a pivotal role in determining the outcome of HPV infection. Viruses and associated neoplastic cells are proposed to have evolved mechanisms to avoid immune attack. T-cell-mediated immune responses against oncogenic HPV are believed to play a central role in cervical carcinogenesis. The presence of HPV-specific cytotoxic T lymphocytes (CTL) in a majority of human cervical cancer patients provides an approach for further study of their functional role in modulating this malignancy. Tumor-infiltrating lymphocytes (TIL) develop as manifestations of the recognition and defense against malignant cells by the host immune system. Cancer cells may overcome immune surveillance, either by downregulating the proliferation of HPV-specific CTL, or altering the effector compositions of immune cells against HPV infections. TIL in the tumor microenvironment can be functionally inhibited and lose the ability of clonal proliferation as a result of depressed expression of IL-2Ralpha. The upregulation of inhibitory signaling relates to the modulation of the virus- and/or tumor-specific immune responses. Alteration of host genetic susceptibility may also lead to abnormal immune response as a general genomic instability resulting from virus persistence. Induction of HPV-specific immune responses is anticipated as an intimate point for the treatment of cervical neoplasia.

The oncogenic potential of human papillomaviruses: a review on the role of host genetics and environmental cofactors

Human papillomaviruses (HPVs), with over 100 genotypes, are a very complex group of human pathogenic viruses. In most cases, HPV infection results in benign epithelial proliferations (verrucae). However, oncogenic types of HPV may induce malignant transformation in the presence of cofactors. For example, over 99% of all cervical cancers and a majority of vulval, vaginal, anal and penile cancers are the result of oncogenic HPV types. Such HPV types have been increasingly linked to other epithelial cancers involving the skin, larynx and oesophagus. Although viral infection is necessary for neoplastic transformation, evidence suggests that host and environmental cofactors are also required. Research investigating HPV oncogenesis is complex and quite extensive. The inability to produce mature HPV virions in animal models has been a major limitation in fully elucidating the oncogenic potential and role of associated cofactors in promoting malignant transformation in HPV-infected cells. We have reviewed the literature and provide a brief account of the current understanding of HPV oncogenesis, emphasizing the role of genetic susceptibility, immune response, and environmental and infectious cofactors.

HLA-DQB1 polymorphisms and risk for cervical cancer: A case-control study in a southern Chinese population

OBJECTIVES AND METHODS

HLA II DQB1 polymorphisms have been shown to associate with cervical cancer risk, but results varied among different populations. In this study, the HLA DQB1 alleles among 221 southern Chinese women with cervical intraepithelial neoplasia grade III (CIN III)/invasive cervical carcinoma (ICC) were compared to 191 controls.

RESULTS

The frequency of DQB1*03 was significantly lower among ICC overall as compared to controls (65.4% vs. 79.1%, odds ratio [95% confidence interval]: 0.50 [0.28-0.88], corrected p-value: 0.04). The protective association of DQB1*03 remained significant for human papillomavirus (HPV) 16-positive ICC, but not for HPV16-negative cases. This is in contrast to studies on European populations where DQB1*03 was associated with an increased risk for ICC. In the current study, 70.1% of the HPV16 isolates were Asian variants, and 28.0% were European variants. However, no significant association between HPV16 variant and DQB1*03 distribution was observed. HPV52 and HPV58 were found respectively in 16.3% and 10.0% of CIN III/ICC, which were higher compared to that of Europe and North America. Further analyses revealed a positive risk association between DQB1*06 and HPV58-positive CIN III/ICC (3.68 [1.37-9.92], corrected p-value: 0.012).

CONCLUSION

The host genetics and the distribution of HPV types/variants may account for the observed differences among southern Chinese and other populations.

Integrated human papillomavirus types 52 and 58 are infrequently found in cervical cancer, and high viral loads predict risk of cervical cancer

OBJECTIVE

The aim of this prospective study was to analyze whether integration or high viral loads of human papillomavirus (HPV) is essential for malignant transformation of HPV types 52 and 58 as well as types 16 and 18.

METHODS

Cervical swabs from 178 consecutive patients, including 81 with invasive cervical cancers and 97 with cervical intraepithelial neoplasias (CIN) II-III, were collected and examined to determine the physical status and viral load of HPV types 16, 18, 52 and 58 DNA using genechip and real-time PCR (polymerase chain reaction) analysis.

RESULTS

In cervical cancer patients, the integrated form of HPV 52 and 58 DNA was found in 25.0% and 12.5% of swabs, respectively; while HPV16 and 18 DNA was found in 82.6% and 100% of swabs, respectively (P < 0.01, for pair-wise comparison of types 16, 18 versus types 52, 58). The viral loads reflected by the amount of E6 for HPV 16, 18, or 52 were significantly increased in invasive cervical cancer compared to CINII-III (P = 0.022 for type 16, P = 0.003 for type18, and P = 0.001 for type 52, respectively). Area under the receiver operating characteristic (ROC) curve for cervical cancer versus CIN II-III was 73.8%, 92.9%, and 88.5% for HPV 16, 18, and 52, respectively, indicating that real-time PCR had good diagnostic value in differentiating cervical cancer from CIN II-III.

CONCLUSIONS

Infrequent integration of HPV 52 and 58 DNA in cervical cancer suggests that it is not prerequisite for progression to cervical cancer. High viral loads (E6) of HPV 16, 18, and 52 DNA may be predictive of the transition of CIN II-III to cervical cancer. Our results indicate that both viral DNA physical status and viral loads of HPV are important factors in the carcinogenesis of different HPV types.

HPV-mediated cervical carcinogenesis: concepts and clinical implications

Persistent infection with a high-risk human papillomavirus (hrHPV) is generally accepted as a necessary cause of cervical cancer. However, cervical cancer is a rare complication of an hrHPV infection since most such infections are transient, not even giving rise to cervical lesions. On average, it takes 12-15 years before a persistent hrHPV infection may ultimately, via consecutive premalignant stages (ie CIN lesions), lead to an overt cervical carcinoma. This argues that HPV-induced cervical carcinogenesis is multi-step in nature. In this review, the data from hrHPV-mediated in vitro transformation studies and those obtained from analysis of clinical specimens have been merged into a cervical cancer progression model. According to this model, a crucial decision maker in the early stages following infection involves individual susceptibility for certain HPV types depending on the genetic make-up of immune surveillance determinants. Once a CIN lesion has developed, altered transcriptional regulation of the viral E6/E7 oncogenes, resulting in genomic instability and distinguishing the process of cell transformation from a productive viral infection, probably provides the subsequent important step towards malignancy. The additional (epi)genetic alterations that subsequently accumulate in high-grade CIN lesions may result in overt malignancy via immortality and growth conditions that gradually become less sensitive to growth-modulating influences mediated by cytokines and cell-cell and cell-matrix adhesions. The potential implications of hrHPV testing and some other biomarkers deduced from this model for cervical screening and the clinical management of CIN disease are also discussed.

Determination of viral load thresholds in cervical scrapings to rule out CIN 3 in HPV 16, 18, 31 and 33-positive women with normal cytology

An increased high-risk human papillomavirus (hrHPV) viral load in cervical scrapings has been proposed as a determinant for high-grade cervical intraepithelial neoplasia (CIN) and cervical cancer (> or =CIN 2), but data so far for HPV types different from HPV 16 are limited and inconsistent. In addition, a viral load threshold to distinguish hrHPV positive women without > or =CIN 2 still has not been defined. Here, we used baseline cervical scrapings of women with normal cytology participating in a large population-based cervical screening trial (i.e. POBASCAM) who were GP5+/6+-PCR positive for 4 common hrHPV types, i.e. HPV 16, 18, 31 or 33, as a reference to arbitrarily define various viral load thresholds (i.e. 25th, 33rd, 50th, 67th and 75th percentiles of the lowest viral load values) for distinguishing women having single infections with these types without high-grade CIN. Viral load assessment was performed by real time type-specific PCR. The viral load threshold values were subsequently validated on abnormal cervical scrapes of 162 women with underlying, histologically confirmed CIN lesions containing 1 of these 4 hrHPV types. All 59 women with CIN 3 had viral load levels that were higher than those of 33% of the women with normal cytology containing the respective hrHPV type detectable by GP5+/6+-PCR (i.e. higher than the 33rd percentile of viral load). By using this 33rd percentile viral load cut-off, sensitivity for CIN 3 of 100% (95% CI 93.9-100) was obtained. Hence, application of this viral load threshold would increase the specificity of HPV testing for HPV 16, 18, 31 and 33-associated prevalent CIN 3 without the cost of a marked reduction in sensitivity. In practice, on the basis of viral load analysis, a less aggressive management can be foreseen for 33% of the women with normal cytology participating in a population-based screening program who are GP5+/6+-PCR positive for HPV 16, 18, 31 or 33.

HPV testing in cervical screening

High-risk human papillomavirus (hrHPV) bearing cervical intraepithelial neoplasia (CIN) is considered, as the real precursor lesion of cervical cancer and persistence of an hrHPV infection is necessary for the progression to cervical cancer. This knowledge warrants the use of hrHPV testing as an adjunct to cervical cytology in population-based screening programmes and for monitoring therapy efficacy of high-grade CIN lesions. Replacement of cytology by hrHPV testing altogether is considered, but for this to be (cost-) effective, accurate information about the specificity of the hrHPV test is required. Additional test systems that can be used to stratify women with a positive hrHPV test are HPV genotyping, viral load analysis and hrHPV mRNA analysis. The need for HPV genotyping of cervical smears is illustrated by the increased risk for high-grade cervical lesions associated with HPV types 16 and 18. In particular, for women who have normal but persistently (>1 year) HPV18-positive smears, endocervical curettage is suggested (evidently considering the age and possible future pregnancies of the respective woman) because HPV18 is associated with glandular lesions in the cervix, which are difficult to detect by cytology.