HLA and susceptibility to cervical neoplasia

Human Leucocyte Antigen Class II Risk and Protective Alleles in Women with Cervical Intraepithelial Neoplasia

Background

Persistent human papillomavirus (HPV) infection is a necessary cause for development of cervical precancerous lesions and cervical cancer, however, only a small percentage of women progress to cervical cancer. The local immune response, determined, among other factors, by Human Leucocyte Antigen (HLA) genes, is thought to be significant. Still the results of genome studies are inconsistent and differ between ethnical populations. The aim of the study was to assess an association between HLA-DQA1*; DQB1*; DRB1* allele's genetic variants between women with cervical precancerous lesions and healthy controls in Latvia.

Materials and methods

From January until April 2017 we enrolled 84 consecutive patients referred for colposcopy to Riga East University Hospital (Latvia) due to abnormal cervical cytology results. 57 women who came for a regular check-up and had normal cytology smears were included in the control group. Material from the cervix was taken for subsequent HLA genotyping of 13 DRB1*, 8 DQA1*, and 12 DQB1* alleles. Colposcopy was performed on all participants. In case of visual suspicion for CIN cervical biopsy was done.

Results

There were 57 "no CIN" patients, 23 histologically proven CIN 1 and 61 CIN2+ cases in the study population. CIN2+ was more often associated with DQA1*0401 (OR 6.68, 95% CI 1.47-30.29, p=0.014), DRB*15 (OR 2.99, 95% CI 1.22-7.39, p=0.017), DQB1*0401 (OR 2.91, 95%CI 1.11-7.68, p=0.03), DQA1*0103 (OR 2.72, 95% CI 1.02-7.21, p=0.045), DRB1*11 (OR 2.42, 95% CI 1.10-5.33, p=0.029) and DQB1*0301 (OR 1.94, 95% CI 1.12-3.38, p=0.018). Women with "no CIN" more often had DQB1*0501 (OR 0.17, 95% CI 0.04-0.81, p=0.026), DRB1*16 (OR 0.21, 95% CI 0.06-0.78, p=0.019), DQA1*0301 (OR 0.35, 95% CI 0.14-0.87, p=0.024) and DRB1*14 (OR 0.59, 95% CI 0.01-0.46, p=0.007).

Conclusions

In the current study we have demonstrated a strong association with risk and protective HLA class II alleles that are determined by the HLA-DRB1*; DQA1*; DQB1*.

Human Papillomavirus 16 E6 Suppresses Transporter Associated with Antigen-Processing Complex in Human Tongue Keratinocyte Cells by Activating Lymphotoxin Pathway

Simple Summary

There is still limited knowledge of the critical pathogenic processes by which HPV16 induces oral carcinogenesis. Therefore, we aimed to illuminate the oncogenic role of HPV16 in the context of oral squamous cell carcinomas (OSCCs). Using human tongue keratinocyte cells, we demonstrated that HPV16 E6 promotes LTα₁β₂ and LTβR expression, thus promoting the lymphotoxin signaling pathway and leading to suppression of the transporter associated with the antigen-processing complex (TAPs; TAP1 and TAP2). Additionally, in vitro, we also demonstrated regulation of the antigenic peptide-loaded machinery in HPV-infected OSCC tissues through analysis of the transcriptomic profiles of the head and neck squamous cell carcinoma (HNSCC) cohort from the TCGA database, which was validated using fresh biopsied specimens. Thus, our study enhances the proposed functional role of HPV16 E6-associated immune-evasive properties in oral epithelial cells, revealing a possible mechanism underlying the development of HPV-mediated OSCCs.

Abstract

Infection by high-risk human papillomaviruses (hrHPVs), including HPV type 16 (HPV16), is a major risk factor for oral squamous cell carcinomas (OSCCs). However, the pathogenic mechanism by which hrHPVs promote oral carcinogenesis remains to be elucidated. Here, we demonstrated that the suppression of a transporter associated with the antigen-processing complex (TAPs; TAP1 and TAP2), which is a key molecule in the transportation of viral antigenic peptides into MHC class-I cells, is affected by the E6 protein of HPV16. Mechanistically, HPV-mediated immune evasion is principally mediated via the signal-transduction network of a lymphotoxin (LT) pathway, in particular LTα₁β₂ and LTβR. Our analysis of transcriptomic data from an HNSCC cohort from the Cancer Genome Atlas (TCGA) indicated that expression of TAP genes, particularly TAP2, was downregulated in HPV-infected cases. We further demonstrated that LTα₁β₂ and LTβR were upregulated, which was negatively correlated with TAP1 and TAP2 expression in HPV-positive clinical OSCC samples. Taken together, our findings imply that HPV16 E6 regulates the machinery of the antigenic peptide-loading system and helps to clarify the role of oncogenic viruses in the context of oral carcinoma.

In Silico Model Estimates the Clinical Trial Outcome of Cancer Vaccines

Over 30 years after the first cancer vaccine clinical trial (CT), scientists still search the missing link between immunogenicity and clinical responses. A predictor able to estimate the outcome of cancer vaccine CTs would greatly benefit vaccine development. Published results of 94 CTs with 64 therapeutic vaccines were collected. We found that preselection of CT subjects based on a single matching HLA allele does not increase immune response rates (IRR) compared with non-preselected CTs (median 60% vs. 57%, p = 0.4490). A representative in silico model population (MP) comprising HLA-genotyped subjects was used to retrospectively calculate in silico IRRs of CTs based on the percentage of MP-subjects having epitope(s) predicted to bind ≥ 1–4 autologous HLA allele(s). We found that in vitro measured IRRs correlated with the frequency of predicted multiple autologous allele-binding epitopes (AUC 0.63–0.79). Subgroup analysis of multi-antigen targeting vaccine CTs revealed correlation between clinical response rates (CRRs) and predicted multi-epitope IRRs when HLA threshold was ≥ 3 (r = 0.7463, p = 0.0004) but not for single HLA allele-binding epitopes (r = 0.2865, p = 0.2491). Our results suggest that CRR depends on the induction of broad T-cell responses and both IRR and CRR can be predicted when epitopes binding to multiple autologous HLAs are considered.

Inside the pocket: Critical elements of HLA-mediated susceptibility to cervical precancerous lesions

Human papillomavirus (HPV) infection is a necessary cause for cervical cancer (CC), but it also depends on genetic factors, such as HLA polymorphism. However, few reports addressed the role of amino acids residues at the HLA peptide-binding cleft in HPV-related cervical disease. Therefore, we aimed to investigate the association between HLA-B, HLA-C, and HLA-DRB1 polymorphism and amino acid residues composing the pockets of the peptide-binding cleft of the respective polypeptide chains with cervical intraepithelial neoplasia (CIN II/III). HLA typing was performed by PCR-SSOP in 184 women with CIN II/III and 174 controls from South Brazil. Associations were estimated by multivariate logistic regression. FDR test was performed to correct the p-value for multiple comparisons. HLA-DRB1*13:01 was associated with protection against CIN II/III, while HLA-C*03:04 was associated with susceptibility. The amino acid residues isoleucine, tyrosine, and leucine at positions 95, 116, and 163 of HLA-C, respectively, were associated with CIN II/III susceptibility. In contrast, serine at positions 11 and 13 of HLA-DRB1 was associated with protection against the disease. Our results confirm previously reported associations between HLA and cervical diseases caused by HPV and suggest a role for amino acid residues at different positions of HLA-C and HLA-DRB1 in CIN II/III. This finding may be further explored to better understand the genetic risk and the influence of immune response to CC development.

Association of HLA-A, -B, DRB, and DQB Alleles with Persistent HPV-16 Infection in Women from Tamil Nadu, India

Women with persistent human papillomavirus (HPV) infections have a high risk of developing cervical cancer (CaCx). HPV-16 alone accounts for more than 60% of CaCx worldwide. Most of the HPV infections are transient and only a subset of women develop persistent HPV-16 infection. Many studies have shown associations of different human leukocyte antigen (HLA) alleles with HPV-mediated CaCx, but there are only a few studies globally that relate to persistent HPV-16 infection. Furthermore, such studies from India are sparse. Hence, we investigated the association of HLA-A, B, DRB, and DQB alleles with persistent HPV-16 infection and HPV-16-positive CaCx in south India (Tamil Nadu). HPV-16 persistent infection was observed in 7% of normal women. A total of 50 women with HPV-16-positive CaCx, 21 women with HPV-16 persistent infection, and 74 HPV-16-negative normal women were recruited for this study. Low-resolution typing of HLA-A, B, DRB, and DQB alleles was performed. HLA-B*44 and DRB1*07 showed a significant association with persistent HPV-16 infection (odds ratio, p-value = 26.3, 0.03 and 4.7, 0.01, respectively). HLA-B*27 and DRB1*12 were significantly associated with both HPV-16⁺ CaCx and persistent HPV-16 infection (23.8, 0.03; 52.9, 0.01; 9.8, 0.0009; and 13.8, 0.009; respectively). HLA-B*15 showed a negative association with HPV-16-positive CaCx (0.1, 0.01), whereas DRB1*04 exhibited protection to both HPV-16-positive CaCx and persistent HPV-16 infection (0.3, 0.0001 and 0.1, 0.0002, respectively). Thus, we show HLA allelic association with HPV-16 infection in Tamil Nadu. Larger studies on high-resolution HLA typing coupled with HPV-16 genome diversity will offer further insights into host/pathogen genome coevolution.

HLA and KIR Associations of Cervical Neoplasia

Background

Cervical cancer is the fourth most common cancer in women, and we recently reported human leukocyte antigen (HLA) alleles showing strong associations with cervical neoplasia risk and protection. HLA ligands are recognized by killer immunoglobulin-like receptors (KIRs) expressed on a range of immune cell subsets, governing their proinflammatory activity. We hypothesized that the inheritance of particular HLA-KIR combinations would increase cervical neoplasia risk.

Methods

Here, we used HLA and KIR dosages imputed from single-nucleotide polymorphism genotype data from 2143 cervical neoplasia cases and 13858 healthy controls of European decent.

Results

The following 4 novel HLA alleles were identified in association with cervical neoplasia, owing to their linkage disequilibrium with known cervical neoplasia-associated HLA-DRB1 alleles: HLA-DRB3*9901 (odds ratio [OR], 1.24; P = 2.49 × 10-9), HLA-DRB5*0101 (OR, 1.29; P = 2.26 × 10-8), HLA-DRB5*9901 (OR, 0.77; P = 1.90 × 10-9), and HLA-DRB3*0301 (OR, 0.63; P = 4.06 × 10-5). We also found that homozygosity of HLA-C1 group alleles is a protective factor for human papillomavirus type 16 (HPV16)-related cervical neoplasia (C1/C1; OR, 0.79; P = .005). This protective association was restricted to carriers of either KIR2DL2 (OR, 0.67; P = .00045) or KIR2DS2 (OR, 0.69; P = .0006).

Conclusions

Our findings suggest that HLA-C1 group alleles play a role in protecting against HPV16-related cervical neoplasia, mainly through a KIR-mediated mechanism.

Human Leukocyte Antigen (HLA) Class II -DRB1 and -DQB1 Alleles and the Association with Cervical Cancer in HIV/HPV Co-Infected Women in South Africa

Background: A subset of women who are co-infected with Human Immunodeficiency Virus type 1 (HIV) and Human papillomavirus (HPV), progress rapidly to invasive cervical cancer regardless of antiretroviral therapy (ART) or immune status. We posit that HIV/HPV co-infection along with specific host HLA II -DRB1 and -DQB1 alleles play a major role in cervical cancer development.

Methodology: We conducted a hospital-based genetic susceptibility case-control study in Cape Town, South Africa. We recruited 256 women of the same race, from which a total of 624 HLA-DRB1 and -DQB1 class II genotypes were studied. We characterized HLA II candidate genes using PCR based, Luminex intermediate resolution genotyping and confirmed significant associated genotypes at four-digit resolution by high resolution gel typing. We analyzed 160 alleles from cancer, 64 alleles from pre-cancer and 400 alleles from healthy control women. Whole blood was used for HIV antibody test and HLA II typing. Cervical tumor tissue biopsies were used for HPV genotyping. Tests were statistically significant if p<0.05.

Results: Women who were co-infected with HIV/HPV had advanced cervical disease compared to women who were HIV negative. HLA class II -DQB1*03:01 and -DQB1*06:02 alleles were associated with cervical cancer in HIV/HPV co-infected women (p=0.001 and p<0.0001, respectively) while HLA class II -DRB1*13:01 and -DQB1*03:19 were rare or absent in women with cervical disease when compared to the control population (p=0.012 and 0.011, respectively).

Conclusion: We describe associations between HLA class II genotypes with cervical cancer, or likely protection from cervical cancer disease in HIV/HPV co-infected South African women. Identifying mechanisms that give rise to this likely protective HLA association will provide insight into development of immune-based prevention measures.

Genetic Susceptibility for Cervical Cancer in African Populations: What Are the Host Genetic Drivers?

Human papillomavirus (HPV) is an essential but not a sufficient cervical cancer etiological factor. Cancer promoters, such as host genetic mutations, significantly modulate therapeutic responses and susceptibility. In cervical cancer, of interest have been viral clearing genes and HPV oncoprotein targets, for which conflicting data have been reported among different populations. This expert analysis evaluates cervical cancer genetic susceptibility biomarkers studied in African populations. Notably, the past decade has seen Africa as a hotbed of biomarker and precision medicine innovations, thus potentially informing worldwide biomarker development strategies. We conducted a critical literature search in PubMed/MEDLINE, Google Scholar, and Scopus databases for case-control studies reporting on cervical cancer genetic polymorphisms among Africans. We found that seven African countries conducted cervical cancer molecular epidemiology studies in one of Casp8, p53, CCR2, FASL, HLA, IL10, TGF-beta, and TNF-alpha genes. This analysis reveals a remarkable gap in cervical cancer molecular epidemiology among Africans, whereas cervical cancer continues to disproportionately have an impact on African populations. Genome-wide association, whole exome- and whole-genome sequencing studies confirmed the contribution of candidate genes in cervical cancer. With such advances and omics technologies, the role of genetic susceptibility biomarkers can be exploited to develop novel interventions to improve current screening, diagnostic and prognostic methods worldwide. Exploring these genetic variations is crucial because African populations are genetically diverse and some variants or their combined effects are yet to be discovered and translated into tangible clinical applications. Thus, translational medicine and flourishing system sciences in Africa warrant further emphasis in the coming decade.

From HPV Infection to Lesion Progression: The Role of HLA Alleles and Host Immunity

Persistent high-risk human papillomavirus (HPV) infection has been associated with increased risk for cervical precancerous lesions and cancer. The host's genetic variability is known to play a role in the development of cervical cancer. The human leukocyte antigen (HLA) genes are highly polymorphic and have shown to be important risk determinants of HPV infection persistence and disease progression. HLA class I and II cell surface molecules regulate the host's immune system by presenting HPV-derived peptides to T-cells. The activation of T-cell response may vary depending on the HLA allele polymorphism. The engagement of the T-cell receptor with the HPV peptide-HLA complex to create an active costimulatory signal is essential for the activation of the T-cell response. Functional peptide presentation by both HLA class I and II molecules is needed to activate efficient helper and effector T-cell responses in HPV infection recognition and clearance. Some of these HLA risk alleles could also be used as preventive tools in the detection of HPV-induced cervical lesions and cancer. These HLA alleles, together with HPV vaccines, could potentially offer possible solutions for reducing HPV-induced cervical cancer as well as other HPV-related cancers.

Replication of results from a cervical cancer genome-wide association study in Taiwanese women

Genetic epidemiological studies show that genetic factors contribute significantly to cervical cancer carcinogenesis. Several genome-wide association studies (GWAS) have revealed novel genetic variants associated with cervical cancer susceptibility. We aim to replicate 4 GWAS-identified single nucleotide polymorphisms (SNPs), which were associated with invasive cervical cancer in Chinese women, in a Taiwanese population. The rs13117307 C/T, rs8067378 A/G, rs4282438 G/T, and rs9277952 A/G SNPs were genotyped in 507 women with cervical squamous cell carcinoma (CSCC) and 432 age/sex matched healthy controls by using TaqMan PCR Assay. Human papillomavirus (HPV) DNA test and typing were performed in CSCC patients. Only the rs4282438 SNP was found to be significantly associated (G allele, odds ratio [OR] = 0.67, P = 1.5 × 10⁻⁵). This protective association remained in HPV-16 positive CSCC subgroup (G allele, OR = 0.60, P = 1.2 × 10⁻⁵). In conclusion, our study confirms the association of rs4282438 SNP with CSCC in a Taiwanese population. However, larger sample sets of other ethnic groups are required to confirm these findings.

Pooled analysis of genome-wide association studies of cervical intraepithelial neoplasia 3 (CIN3) identifies a new susceptibility locus

Recent genome-wide association studies (GWASs) in subjects of European descent have identified associations between cervical cancer risk and three independent loci as well as multiple classical human leukocyte antigen (HLA) alleles at 6p21.3. To search for novel loci associated with development of cervical cancer, we performed a pooled analysis of data from two GWASs by imputing over 10 million genetic variants and 424 classical HLA alleles, for 1,553 intraepithelial neoplasia 3 (CIN3), 81 cervical cancer and 4,442 controls from the Swedish population. Notable findings were validated in an independent study of 961 patients (827 with CIN3 and 123 with cervical cancer) and 1,725 controls. Our data provided increased support for previously identified loci at 6p21.3 (rs9271898, P = 1.2 × 10⁻²⁴; rs2516448, 1.1 × 10⁻¹⁵; and rs3130196, 2.3 × 10⁻⁹, respectively) and also confirmed associations with reported classical HLA alleles including HLA-B*07:02, -B*15:01, -DRB1*13:01, -DRB1*15:01, -DQA1*01:03, -DQB1*06:03 and -DQB1*06:02. In addition, we identified and subsequently replicated an independent signal at rs73730372 at 6p21.3 (odds ratio = 0.60, 95% confidence interval = 0.54–0.67, P = 3.0 × 10⁻¹⁹), which was found to be an expression quantitative trait locus (eQTL) of both HLA-DQA1 and HLA-DQB1. This is one of the strongest common genetic protective variants identified so far for CIN3. We also found HLA-C*07:02 to be associated with risk of CIN3. The present study provides new insights into pathogenesis of CIN3.

Impact of genetic variations and transcriptional alterations of HLA class I genes on cervical cancer pathogenesis

In a novel attempt to understand the variations in DNA sequences underlying HLA class I alleles associated with HPV16-related CaCx, we determined the alleles by reconstructing SNP-based haplotypes from resequencing of the most polymorphic exons 2 and 3 of HLA-A, HLA-B and HLA-C. We also determined the impact of SNPs and transcriptional alterations of the genes on CaCx. A high density of SNPs was identified from resequencing. HLA expression was determined by real-time PCR. We identified that even a single associated HLA allele had many underlying SNP-based haplotypes. Out of the most frequent (≥5%) HLA class I alleles, HLA-B*40:06 and HLA-B*15:02 respectively imparted significant risk towards and protection from CaCx as well as HPV16 infection. Employing median-joining networks to detect clusters of sequence-variations for specific HLA alleles, we found the protective SNP-based signature, GAATTTA, in all SNP-based haplotypes of HLA-B*15:02 allele. The signature was derived from seven SNPs within HLA-B which were newly associated with the disease. Contrarily, similarly derived risk-signature, TTGCGCC, mapped only to 52% of SNP-based haplotypes of HLA-B*40:06 allele. This indicated that all SNP-based haplotypes underlying a particular associated HLA allele might or might not have a single signature of risk/protection. HLA-A, HLA-B and HLA-C expressions were downregulated among CaCx cases compared to asymptomatic infections and HPV-negative controls. HLA-A and HLA-B were repressed in both cases harbouring episomal and integrated HPV16, whereas HLA-C in only the latter. Novel genetic variations and differential downregulation-patterns of HLA class I have a significant bearing on HPV16-related CaCx pathogenesis.

Identification of the impact on T- and B- cell epitopes of human papillomavirus type-16 E6 and E7 variant in Southwest China

Cervical cancers almost are infected by human papillmavirus (HPV), encoding E6 and E7 oncoproteins which are regard as ideal targets on the mechanism of this disease and development of vaccines. HLA (human leukocyte antigen) participates in the local immune response to prevent tumor invasion and progression. But due to highly polymorphism of HLA, prediction shows its importance in this study. More effective immunoinformatics was used for predicting epitopes from HPV-16 E6 and E7, including T- and B-cell epitopes. Eight substitutions are detected. Specifically speaking, for HLA-I, HLA-A*33:03 (26), HLA-B*13:01 (14), HLA-C*03:02 (5) for E6 and HLA-A*02:01 (6), HLA-B*40:01 (5), HLA-C*03:04 (4) for E7 are most frequency. Epitope _41-48EVYDFAFR for HLA-A*33:03 (0.1) for E6 has best binding affinity, as well as HLA*02:01 and HLA-B*40:01 (0.2) for E7. The mutations of D25E and L83V of E6 and N29S of E7 produce new epitopes, and the percentile values change with them. For HLA-II, seventeen epitopes in the reference at percentile value from 0.22 to 4.76, while in variant from 0.22 to 4.96. For the B-cell epitopes, three most potent epitopes for E6 were listed, and N29S lead the growth of score from 0.81 to 0.83. In summary, E6_40-55REVYDFAFRDLCIVYR and E7_11-22YMLDLQPETTDL are the important regions, containing the majority of predicted epitopes. E6 72-83 for HLA-A*02:01 and E6 74-84 for HLA-B*15:02 maybe are the new direct for therapeutic vaccine aimed at L83V variants. HLA-DRB1*15:02 is better binder with T cell in our HLA class II. It is a systematic, detail recognition for T- and B-cell epitopes of HPV-16 E6 and E7 from Southwest China, which may be helpful to design vaccines specifically for women in Southwest China and testing methods specifically for this region. The results of our study may contribute to future researches on vaccines improvement, or screening methods for a particular population.

HLA-DRB1 Class II antigen level alleles are associated with persistent HPV infection in Mexican women; a pilot study

BACKGROUND

Persistent infection with high-risk human papillomavirus (HPV) is a major risk factor for malignant lesions and cervical cancer. A widely studied element in the search for genetic factors influencing risk HPV infection diseases is allelic variation of the human leukocyte antigen (HLA) locus. The study was designed to search for HLA susceptibility alleles contributing to the persistence of HPV infection in Mexican women.

METHODS

A total of 172 subjects were divided into three groups: 1) HPV-persistent patients; 2) HPV-cleared; and 3) HPV-reinfected patients. They were screened for HPV types using a polymerase chain reaction (PCR). PCR-sequence specific oligonucleotide probes (PCR-SSOP) was used for HLA DRB1 and DQB1 typing.

RESULTS

We observed that HLA-DQB1*0501 allele might be associated with susceptibility of reinfection with HPV (p = 0.01, OR = 4.9, CI 95% = 1.3 -18.7). Allele frequency of HLA-DRB1*14 was particularly reduced in patients with cancer when compared with the HPV-persistent group (p = 0.04), suggesting that this allele is a possible protective factor for the development of cervical cancer (OR = 2.98). HLA-DRB1*07 might be associated with viral clearance (p = 0.04).

CONCLUSIONS

Genetic markers for HPV infection susceptibility are different in each population, in Mexicans several HLA-DQB1 alleles might be associated with an enhanced risk for viral persistence. In contrast, DRB1*14, seems to confer protection against cervical cancer.

Genome-wide association study of susceptibility loci for cervical cancer

BACKGROUND

Cervical carcinoma has a heritable genetic component, but the genetic basis of cervical cancer is still not well understood.

METHODS

We performed a genome-wide association study of 731 422 single nucleotide polymorphisms (SNPs) in 1075 cervical cancer case subjects and 4014 control subjects and replicated it in 1140 case subjects and 1058 control subjects. The association between top SNPs and cervical cancer was estimated by odds ratios (ORs) and 95% confidence intervals (CIs) with unconditional logistic regression. All statistical tests were two-sided.

RESULTS

Three independent loci in the major histocompatibility complex (MHC) region at 6p21.3 were associated with cervical cancer: the first is adjacent to the MHC class I polypeptide-related sequence A gene (MICA) (rs2516448; OR = 1.42, 95% CI = 1.31 to 1.54; P = 1.6×10(-18)); the second is between HLA-DRB1 and HLA-DQA1 (rs9272143; OR = 0.67, 95% CI = 0.62 to 0.72; P = 9.3×10(-24)); and the third is at HLA-DPB2 (rs3117027; OR=1.25, 95% CI = 1.15 to 1.35; P = 4.9×10(-8)). We also confirmed previously reported associations of B*0702 and DRB1*1501-DQB1*0602 with susceptibility to and DRB1*1301-DQA1*0103-DQB1*0603 with protection against cervical cancer. The three new loci are statistically independent of these specific human leukocyte antigen alleles/haplotypes. MICA encodes a membrane-bound protein that acts as a ligand for NKG2D to activate antitumor effects. The risk allele of rs2516448 is in perfect linkage disequilibrium with a frameshift mutation (A5.1) of MICA, which results in a truncated protein. Functional analysis shows that women carrying this mutation have lower levels of membrane-bound MICA.

CONCLUSIONS

Three novel loci in the MHC may affect susceptibility to cervical cancer in situ, including the MICA-A5.1 allele that may cause impaired immune activation and increased risk of tumor development.

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.

The detection of circulating human papillomavirus-specific T cells is associated with improved survival of patients with deeply infiltrating tumors

A detailed analyses of HPV-specific immunity was performed in a large group of patients with HPV-induced cervical cancer (CxCa) in relation to HLA-types and prognostic factors. Patients were HLA-typed and HPV16/18-specific T-cell immunity was assessed by proliferation assay and cytometric bead array using freshly isolated PBMC and by phenotypic analysis of HPV-specific T cells. The results were analyzed in relation to known disease-related HLA-types (DR7, DR13, DR15/DQ06), invasion-depth and size of tumor, lymph node (LN) status and disease free survival. In total 119 HLA-typed patients with CxCa were analyzed. Patients expressing the HLA-DR13 haplotype were underrepresented as compared to the Dutch population (p = 0.014), whereas HLA-DR7 was overrepresented in patients with HPV16+ CxCa (p = 0.006). In 29 of 94 patients (31%) from whom blood could be tested, a proliferative response to HPV16/18 was detected, which was associated with increased numbers of HPV-specific CD4+CD25+ (activated) T cells (p = 0.03) and HPV-specific CD4+CD25+FoxP3-positive T cells (p = 0.04). The presence of both FoxP3-positive and negative HPV-specific CD4+CD25+ T cells was significantly correlated (p = 0.01). Interestingly, the detection of HPV-specific proliferation was associated with invasion depth (p = 0.020) but not with HLA type, tumor size nor LN status. Moreover, the detection of HPV-specific immunity was associated with an improved disease free survival (p = 0.04) in patients with deeply infiltrating tumors. In conclusion, HPV-specific proliferative T-cell response, comprising higher percentages of HPV-specific CD25+ and CD25+FoxP3-positive CD4+T cells, are more frequently detected in patients with deep infiltrating CxCa tumors and associated with an improved survival.

Undifferentiated nasopharyngeal carcinoma from a nonendemic area: protective role of HLA allele products presenting conserved EBV epitopes

The role of genetic factors involved in the development of undifferentiated nasopharyngeal carcinoma (UNPC) in nonendemic areas has been poorly investigated. High-resolution human leukocyte antigen (HLA) class I genotyping carried out in 82 Italian UNPC patients and 286 bone marrow donors born in the same province showed that A*0201, B*1801, and B*3501, known to efficiently present Epstein-Barr virus (EBV)-derived epitopes, were significantly under-represented in UNPC patients. Moreover, the A*0201/B*1801 haplotype was significantly less frequent in UNPC cases, with a 90% reduced risk (odds ratio [OR] 0.1, 95% confidence interval [CI] = 0.0-0.5) to develop UNPC, suggesting an additive effect. Notably, all 5 BARF1 epitopes and 7 of the 8 LMP-2 epitopes known to bind A*0201 showed a fully conserved sequence in all the 31 Italian EBV isolates investigated. The 4 amino acid changes affecting the 436-447 LMP-2 epitope do not reduce, but rather increase in two cases, the predicted ability of "variant" epitopes to bind the HLA-A*0201 allele, as shown by immunoinformatic analysis. Moreover, a significantly increased risk for UNPC was associated with A*2601 (OR 2.4, 95% CI = 1.1-4.9) and B*4101 (OR 9.2, 95% CI = 2.5-34.3). These findings indicate that Italian UNPC patients have a distinct HLA-A and -B genotypic profile and suggest that the decreased risk for UNPC conferred by definite HLA class I molecules is probably related to their ability to efficiently present LMP-2 and BARF1 epitopes that are highly conserved in EBV isolates from this geographic region. These results have practical implications for the immunotherapy of UNPC.

Human leukocyte antigen frequency in human high-grade gliomas: a case-control study in Sicily

OBJECTIVE

Human leukocyte antigens (HLAs) are widely expressed cell surface molecules that present antigenic peptides to T lymphocytes and modulate immune response against inflammatory and malignant diseases. The aim of this study was to compare HLA distribution in patients with newly diagnosed high-grade gliomas (HGGs) and 2 control groups from a restricted geographic area (eastern Sicily).

METHODS

HLA allele frequency, as determined from peripheral blood of 56 adult patients with HGGs, was compared with that of 2 different control groups: 140 healthy bone marrow donors (group A) and 69 virtually brain tumor-free patients (group B). HLA expression was evaluated using a reverse transcriptase polymerase chain reaction-sequence-specific oligonucleotide probe.

RESULTS

There was significant expression of HLA-A*11 in patients with HGGs compared with control groups A and B (P < 0.003 and P < 0.018, respectively). Significant expression of HLA genotypes in patients with HGGs was also identified for HLA-DQB1*06 (P = 0.005), HLA-DRB1*14 (P = 0.001), and HLA-DRB3*01 (P = 0.007) compared with control group B. In HGG patients, there was statistically significantly decreased expression, compared with control groups A and B, of HLA-B*07 (P = 0.002 and P = 0.03, respectively) and HLA-C*04 (P = 0.007 and P = 0.016, respectively). There was statistically significant lower expression of HLA-C*05 in the HGG group compared with group B (P < 0.03).

CONCLUSION

This is the first study to describe the frequency of distribution of HLAs in a population from a restricted geographic area. The findings suggest a possible correlation between HLA allele distribution and the occurrence of newly diagnosed malignant astroglial brain tumors.

Human papillomavirus 16-specific T cell responses in classic HPV-related vulvar intra-epithelial neoplasia. Determination of strongly immunogenic regions from E6 and E7 proteins

Cell-mediated immunity directed against human papillomavirus 16 (HPV-16) antigens was studied in 16 patients affected with classic vulvar intra-epithelial neoplasia (VIN), also known as bowenoid papulosis (BP). Ten patients had blood lymphocyte proliferative T cell responses directed against E6/2 (14-34) and/or E6/4 (45-68) peptides, which were identified in the present study as immunodominant among HPV-16 E6 and E7 large peptides. Ex vivo enzyme-linked immunospot-interferon (IFN)-gamma assay was positive in three patients who had proliferative responses. Twelve months later, proliferative T cell responses remained detectable in only six women and the immunodominant antigens remained the E6/2 (14-34) and E6/4 (45-68) peptides. The latter large fragments of peptides contained many epitopes able to bind to at least seven human leucocyte antigen (HLA) class I molecules and were strong binders to seven HLA-DR class II molecules. In order to build a therapeutic anti-HPV-16 vaccine, E6/2 (14-34) and E6/4 (45-68) fragments thus appear to be good candidates to increase HPV-specific effector T lymphocyte responses and clear classic VIN (BP) disease lesions.

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.

Human leukocyte antigen class II alleles and risk of cervical cancer in China

Human leukocyte antigen (HLA) class II alleles have been associated with an increased or decreased risk of developing cervical cancer through infection with oncogenic forms of human papillomavirus (HPV). To verify whether HLA class II allelic polymorphism is related to cervical cancer in China, 133 cervical cancers and 98 healthy controls were analyzed for HLA typing. Our results showed that DPB1*1301 allele frequency was significantly higher in the cervical cancers compared with healthy controls (OR, 3.793; p = 0.002; Pc = 0.04). A significant relationship was found between DRB1*150101-DQB1*0602 haplotype (OR, 0.180; p < 0.0001; Pc < 0.003), DRB1*070101-DQB1*0201 haplotype (OR, 0.110; p = 0.001; Pc = 0.03), and decreased risk for cervical cancer. Similar tendencies were observed for DRB1*150101-DQB1*0602 haplotype with HPV16 positive cervical cancers (OR, 0.182; p = 0.001; Pc = 0.021), and for DRB1*070101-DQB1*0201 haplotype (OR, 0.144; p =0.003; Pc = 0.063). These results indicate that HLA-DPB1*1301 may confer susceptibility to cervical cancer, and the haplotypes DRB1*150101-DQB1*0602 and DRB1*070101-DQB1*0201 may contribute to the resistance to the development of cervical cancer among Chinese women. The study suggests that specific HLA class II alleles and haplotypes may influence the immune response to specific HPV-encoded epitopes and affect the risk of cervical cancer in a Chinese population from an area with a high incidence of this neoplasia.

HLA-DRB1 Alleles and Cervical Squamous Cell Carcinoma: Experimental Study and Meta-Analysis

Polymorphisms in human leukocyte antigen (HLA) genes have been implicated in the risk for cervical cancer. Association of certain class II HLA alleles with cervical cancer has been documented in various ethnic populations. The implications of such an association, however, are controversial. We analyzed 126 Chinese women with cervical squamous cell carcinoma (CSCC) and 289 healthy controls to test associations of certain HLA-DRB1 alleles. We then performed meta-analyses combining our own experimental data and data from nine other published studies. We found no significant differences in HLA-DRB1 allele frequencies in both CSCC and HPV-16-positive CSCC patients and control subjects. Meta-analysis provided evidence that four allele families (HLA-DRB1*04, *07, *11, and *15) and seven alleles (HLA-DRB1*0403, *0405, *0407, *0701, *1501, *1502, and *1503) were positively associated and two allele families (HLA-DRB1*09 and *13) and four alleles (HLA-DRB1*0901, *1301, *1302, and *1602) were negatively associated with CSCC in all studies or in Caucasian subgroups. In conclusion, our meta-analysis confirms the apparent association between certain HLA-DRB1 allele families and alleles and CSCC, suggesting that oncogenesis in this disease may be related to defects in immunoregulation. Larger studies may be needed, particularly in various ethnic groups, to further substantiate these associations.

The Relationship Between HLA Class II Polymorphisms and Somatic Deletions in Testicular B Cell Lymphomas of Dutch Patients

Several risk factors including immune deficiencies, infections, and autoimmune diseases have been established for non-Hodgkin's lymphoma (NHL). For diffuse large B cell lymphoma (DLBCL), the most common type of lymphoma, no risk factors have been described, which may be due to the intrinsic heterogeneity of this disorder. Previously we reported that, in contrast to nodal DLBCLs, the majority of testicular DLBCLs manifested complete loss of HLA-DR and -DQ expression associated with homozygous deletions of the corresponding genes. To determine the correlation between HLA class II polymorphisms and these lymphomas, we applied DNA typing for HLA-DRB1 and HLA-DQB1 on 50 Dutch patients with testicular and 48 with nodal DLBCL and compared the frequencies with a cohort of healthy Dutch controls. Both the patients with nodal and those with testicular DLBCL manifested significantly higher frequencies of HLA-DRB1*15 than the controls (p < 0.018, odds ratio 2.09 and p < 0.013, odds ratio 2.12, respectively). Moreover, a positive association was seen with HLA-DRB1*12 (p = 0.043, odds ratio 4.17) in the patients with testicular DLBCL, and a negative association was seen with HLA-DRB1*07 (p = 0.022, odds ratio 0.13) in the patients with nodal DLBCL. Homozygous deletions of the HLA-DR/DQ region, evaluated by interphase fluorescence in situ hybridization were seen in 20 of 48 testicular tumors. No preferential loss or retention of a particular HLA-DR or -DQ allele was seen because all alleles were at least once retained or involved in a homozygous deletion.

HLA-DRB1, -DQB1 alleles in head and neck carcinoma patients

Certain HLA class II alleles have been reported to play a role in development or prevention of cervical carcinoma, an epithelial malignancy linked to human papillomavirus (HPV). In head and neck carcinomas, of which a subset is also HPV associated, the impact of HLA genes remains unknown. HLA-DRB1, -DQB1 alleles were determined in a comprehensive series of 162 head and neck carcinoma patients, for which 83 consecutive cadaveric organ donors of Finnish origin served as controls. DRB1*03 was associated with node-negative disease and DRB1*08 and 13 with small tumors; DRB1*04 was protective against disease relapse. Most alleles of borderline significance in this study act similarly in cervical carcinomas.

Polymorphic amino acids at codons 9 and 37 of HLA-DQB1 alleles may confer susceptibility to cervical cancer among Chinese women

Cervical cancer is strongly associated with the infection by oncogenic forms of human papillomavirus (HPV). Although most women are able to clear HPV infection, some develop persistent infections that may lead to cancer, implying genetic susceptibility factors for malignant progression. To verify whether HLA class II DQB1 polymorphism is related to cervical cancer in Chinese population, HLA-DQB typing was carried out by PCR-SBT for 258 patients with cervical cancer and 284 healthy controls, and the allele frequencies were calculated. In this study, HLA-DQB1*060101 and DQB1*0602 alleles were significantly higher in the HPV16 infected patients with cervical cancer compared with healthy controls (chi(2) = 31.7452, p < 0.0001; chi(2) = 12.7838, p(c) = 0.0066), but DQB1*050201 allele was significantly lower (chi(2) = 26.2187, p < 0.0001). This result indicates that HLA-DQB1*060101 and DQB1*0602 may confer susceptibility to cervical cancer, and DQB1*050201 may contribute to the resistance to the development of cervical cancer among Chinese women. Sequence analysis reveals that DQB1*060101 allele encodes Leu at position 9 and Asp at position 37, unique to the susceptibility to cervical cancer, whereas the other DQB1 alleles encode Phe or Tyr and Ile or Tyr at the same two positions, respectively. This finding implies that polymorphic amino acids at the putative antigen binding residues 9 and 37 of HLA-DQB1 alleles may play an important role in the development of cervical cancer.

HLA-B alleles, high-risk HPV infection and risk for cervical neoplasia in southern Chinese women

A population-based study was conducted on 256 southern Chinese with cervical intraepithelial neoplasia grade III (CIN III) or invasive cervical cancer (ICC) and on 258 controls to examine the associations between HLA-B alleles, infection with high-risk human papillomaviruses (HPVs) and the development of cervical neoplasia. HLA-B15 was found to be protective for CIN III/ICC overall (p(corrected) = 0.003), and for HPV52-positive CIN III/ICC (p(corrected) = 0.003). A marginal protective effect of B15 was observed for HPV16-positive CIN III/ICC, but no significant associations were revealed for HPV18- or HPV58-positive cases. None of the HLA-B alleles were found to confer an increased risk for cervical neoplasia. HLA-B15 is common among Asian for whom HPV52, a worldwide uncommon HPV type, also exists in a relatively high prevalence. It would also be worthwhile to assess the association between HLA-B15, HPV52 and cervical cancer in other Asian populations.

HLA Alleles and Risk of Cervical Intraepithelial Neoplasia Among Southwestern American Indian Women

An increase in cervical intraepithelial neoplasia (CIN) has been described in American Indian women in New Mexico. Differences in human leukocyte antigen (HLA) alleles have been reported in cervical intraepithelial neoplasia (CIN) compared with controls in other populations. We investigated HLA alleles and CIN in Southwest American Indian women. The case control study included 89 women with biopsy-proven CIN II/III (diagnosed November 1994 through October 1997) and 271 similar women with normal cervical epithelium from the same clinics. DRB1, DQB1, and DPB1 alleles were determined using DNA typing techniques. DQA1 and HLA-A allele typing was included for some subjects (randomly chosen n = 37 and n = 163 cases and controls, respectively). We found a decreased risk of CIN with DRB1*1402 (OR 0.5, 95% CI 0.3-0.9) and an increased risk with DRB1*1501 (OR 2.7, 95% CI 0.9-7.3). Additionally, DQA1*0102 was associated with increased risk (OR 4.5, 95% CI 1.3-5.3) and HLA-A*02 with decreased risk (OR 0.4, CI 0.2-0.9). Our findings are discussed along with studies in other populations.

[Contribution of viral typing in cytological anomalies of the cervix]

Management practices for low-grade cervical lesions identified on screening swabs have been modified by research on the HPV. The appropriate approach for low-grade lesions is particularly difficult to determine due to the potential risk of malignant transformation coupled with the cost implications of treating lesions which will heal spontaneously in the majority of patients. The diagnosis of these low-grade lesions can be improved by thin layer swabs which have a greater sensitivity than conventional swabs. The current consensus is that swab results should be expressed according to the Bethesda classification. Routine tests for HPV (Hybrid Capture II) should be reserved for patients with an ASC-US swab. Colposcopy is indicated if the swab is positive for a low-grade lesion followed by cytology if the colposcopy is normal. If there is no evidence of HPV, search for oncogenes can lighten the treatment regimen due to the high specificity of the test. If a low-grade histological lesion (CIN1) is proven, cytocolposcopic surveillance should be proposed, surgical resection being undertaken in colposcopy cannot be performed. Here again search for HPV oncogenes at one year is an interesting alternative if the examination is negative. These practices are applicable in adolescents and HIV- positive patients who are particularly exposed to HPV.

E5 protein of human papillomavirus type 16 selectively downregulates surface HLA class I

Papillomaviruses have evolved mechanisms that result in escape from host immune surveillance. The E5 protein is expressed early in papillomavirus infection in the deep layers of the infected epithelium. It is localized to the Golgi apparatus (GA) and endoplasmic reticulum. The E5 protein of bovine papillomavirus (BPV) impairs the synthesis and stability of major histocompatibility (MHC) class I complexes and prevents their transport to the cell surface due to retention in the GA. Here we show that human papillomavirus type 16 (HPV-16) E5 also causes the retention of MHC (HLA) class I complexes in the GA and impedes their transport to the cell surface, which is rescued by treatment with interferon. Unlike BPV E5, HPV-16 E5 does not affect the synthesis of HLA class I heavy chains or the expression of the transporter associated with antigen processing TAP. These results show that downregulation of surface MHC class I molecules is common to both BPV and HPV E5 proteins. Moreover, we determined that HPV-16 E5 downregulates surface expression of HLA-A and HLA-B, which present viral peptides to MHC class I-restricted cytotoxic T lymphocytes (CTLs), but not the natural killer (NK) cell inhibitory ligands HLA-C and HLA-E. Selective downregulation of cell surface HLA class I molecules may allow the virus to establish infection by avoiding immune clearance of virus-infected cells by both CTLs and NK cells.

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

Human papillomavirus (HPV) infection is the most important risk factor for development of cervical carcinoma. Carriers of certain HLA class II alleles, e.g., DRB1*1501 and DQB1*0602, are more prone to HPV 16 infection and cervical carcinoma, whereas other alleles, e.g., DRB1*1301 and DQB1*0603, render carriers less susceptible to the disease. In our study comprising 484 cases and 601 controls, we examine the effect of HLA class II alleles on viral load of the oncogenic types HPV 18/45 and HPV 31 and risk of developing cervical carcinoma in situ. We find that carriers of the commonly reported protective DRB1*1301 and DQB1*0603 alleles have lower HPV 18/45 load compared to noncarriers and a lower risk of developing HPV 18/45-positive cervical carcinoma. This provides further evidence that the HLA class II-mediated immune response to HPV is important for controlling viral load and outcome of an infection.

Loss of heterozygosity on chromosome 6 in HPV-16 positive cervical carcinomas carrying the DRB1*1501-DQB1*0602 haplotype

High-risk human papillomaviruses (HPVs), specifically HPV-16 and -18, have been associated with the development of carcinoma in situ (CIS) and of invasive cervical cancer (CC). However, only a small fraction of HPV-infected women will show signs of disease progression, suggesting that other factors in the carcinogenic pathway are needed. We previously demonstrated that human leukocyte antigen (HLA) DRB1*1501-DQB1*0602 (high risk) was associated with the development of CIS and CC tumors in HPV-16-positive patients. To characterize the molecular changes that could be relevant to tumor progression, we compared the extent of loss of heterozygosity (LOH) on chromosome 6 in HPV-16-positive CIS patients who were carriers of high-risk and neutral HLA haplotypes. CIS and CC cases demonstrated similar LOH patterns. A wide range of LOH frequencies was found at 6p (10-53%) and 6q (5-28%) in CIS cases, suggesting that LOH is an early event in the carcinogenic process. A comparative analysis of LOH frequencies in the high-risk versus the neutral HLA haplotypes showed a statistically significant difference in the extent of LOH at 6p24-p25 (58.6% versus 25.8%; P = 0.018) and at 6p21.3 (79.3% versus 35.5%; P = 0.001), a region that contains the HLA complex. LOH at this region could affect genes encoding HLA class I-II molecules, as well as factors responsible for the assembly, transport, and stable expression of HLA molecules. These losses may be a reflection of both an abnormal immune response and a general genome-wide instability resulting from virus persistence.

HLA-DRB1*1602 allele is positively associated with HPV cervical infection in Bolivian Andean women

Incidence of cervical cancer is high among Bolivian Andean women. Human papillomavirus (HPV) infection is known as the major risk factor of cervical cancer. The host immune system plays an important role in the outcome of HPV infection and associated malignancies. In order to study the immunogenetic background of Bolivian Andean women with regard to HPV infection status, we compared HLA class I and class II allele frequencies between 37 HPV positive and 68 HPV negative Bolivian women. Demographic variables, including distribution of Andean ethnicities, were similar in both groups. Comparison of HLA class I allele frequencies between both groups indicated no significant difference. In contrast, HLA class II DRB1*1602 allele, an Amerindian allele, was significantly higher in the HPV positive women compared with HPV negative controls (chi(2) = 5.2, p < 0.05, odds ratio = 3.17; 95% confidence interval = 1.4-8.8). HPV types present in the HPV positive group were HPV-18, -16, -31, -33, and -58. These results suggest that HLA class II DRB1*1602 may confer susceptibility to infection with genetically related HPV types. This is the first report of an HLA class II association with HPV infection in an Andean population.

The E5 protein of human papillomavirus type 16 perturbs MHC class II antigen maturation in human foreskin keratinocytes treated with interferon-gamma

Major histocompatibility complex (MHC) class II antigens are expressed on human foreskin keratinocytes (HFKs) following exposure to interferon gamma. The expression of MHC class II proteins on the cell surface may allow keratinocytes to function as antigen-presenting cells and induce a subsequent immune response to virus infection. Invariant chain (Ii) is a chaperone protein which plays an important role in the maturation of MHC class II molecules. The sequential degradation of Ii within acidic endocytic compartments is a key process required for the successful loading of antigenic peptide onto MHC class II molecules. Since human papillomavirus (HPV) 16 E5 can inhibit the acidification of late endosomes in HFKs, the E5 protein may be able to affect proper peptide loading onto the MHC class II molecule. To test this hypothesis, HFKs were infected with either control virus or a recombinant virus expressing HPV16 E5 and the infected cells were subsequently treated with interferon-gamma. ELISAs revealed a decrease of MHC class II expression on the surface of E5-expressing cells compared with control virus-infected cells after interferon treatment. Western blot analysis showed that, in cells treated with interferon gamma, E5 could prevent the breakdown of Ii and block the formation of peptide-loaded, SDS-stable mature MHC class II dimers, correlating with diminished surface MHC class II expression. These data suggest that HPV16 E5 may be able to decrease immune recognition of infected keratinocytes via disruption of MHC class II protein function.

Polymorphism at the -308-promoter position of the tumor necrosis factor-alpha (TNF-alpha) gene and cervical cancer

The purpose of the study was to investigate the hypothesis that the genetically programmed ability to produce low, medium, or high levels of tumor necrosis factor-alpha (TNF-alpha), as determined by TNF-alpha promoter polymorphism at position 308, influenced the development of cancer of the uterine cervix. The population was recruited from patients attending gynecological clinics at two teaching hospitals in Harare, Zimbabwe. Laboratory tests were performed in the Departments of Immunology and Medical Microbiology, Medical School, University of Zimbabwe. One hundred and three patients with invasive cancer of the uterine cervix and 101 healthy women were included in the study. All patients and healthy controls were from the Shona ethnic groups that inhabit northern Zimbabwe. DNA was purified from cervical cytobrush samples obtained from women with cervical cancer. In random cases a second DNA sample was extracted from patient blood. Control DNA was extracted from urine or peripheral blood samples from the healthy women. Detection of allele A and /or G at the 308 position in the promoter region of the TNF-alpha gene was carried out using the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) technique. Polymorphism in the amplified products was detected by gel electrophoresis. There was no statistically significant difference in the distribution of the low (G) or high (A) producer alleles at position 308 of the TNF-alpha gene between patients with cervical cancer and healthy women. The high producer haplotype AA was identified in only one patient with cervical cancer and two healthy women. These data suggest that the genetically acquired ability to produce higher levels of TNF-alpha is present in a minority of women with or without cervical cancer in the Zimbabwean population. Homozygosity for allele 308A is very rare. High-producer allele 308A as well as high-producer haplotypes AA is significantly less common in a Zimbabwean population than in a European population.

TAP1, TAP2, and HLA-DR2 alleles are predictors of cervical cancer risk

OBJECTIVE

The likelihood of developing cervical cancer has been shown to be increased in persons with certain HLA alleles. We evaluated immune response genes in the HLA region of chromosome 6 to see if individual or interactive associations with cervical cancer risk could be identified.

METHODS

Tissue was obtained from 127 women undergoing surgical treatment for cervical cancer. Blood samples were obtained from 175 control subjects. A combination of polymerase chain reaction (PCR), sequence-specific PCR, and DNA sequencing was used to evaluate polymorphic alleles, including HLA class I B7, TNF alpha, HLA class II DR2, TAP1, and TAP2 genes. Fisher's exact test and logistic regression modeling were used for statistical analysis.

RESULTS

A significantly greater proportion of the patients with cervical cancer were found to have the HLA class II DR2 1501 allele (P = 0.023) and the TAP2 A/B heterozygous pattern of alleles (P = 0.0006) than were women without cervical cancer. A proportion of patients with cervical cancer significantly smaller than that of the control women had a polymorphism at the -238 position of the TNF promoter and the TAP1 C/C homozygous pattern of alleles. With logistic modeling, the markers that showed consistent association with the occurrence of cervical cancer were TAP2 A/B, HLA-DR2 1501, and TAP1 C/C.

CONCLUSIONS

We demonstrated a significant association between immune response genes and the risk of cervical cancer. Our data create a compelling argument for a gene or a cluster of genes in the HLA region of chromosome 6 that regulates host immune responses to human papillomavirus infection in a manner that results in inherited susceptibility or resistance to the transforming properties of oncogenic papillomaviruses.

Risk factors related to the development and mortality from invasive cervical cancer clinical utility and impact on prevention

The focus of this article is to explore the various risk factors related to cervical cancer and the practical context in which they can be applied. The ability to link dinical outcomes (disease presence, persistence, progression, and recurrence) with antecedent risk factors is strengthened by a new understanding of the molecular mechanisms that are responsible for malignant transformation.

Host and viral genetics and risk of cervical cancer: a review

Infection with human papillomaviruses (HPV) is known to play a central role in the development of cervical cancer. Both host and viral genetic factors have been postulated to be important determinants of risk of HPV progression to neoplasia among infected individuals. In this report, we review epidemiological studies that have evaluated the role in cervical cancer pathogenesis of genetic variation in human leukocyte antigen (HLA) genes and in the HPV genome itself. A protective effect of HLA Class II DRB1*13/DBQ1*0603 alleles is the most consistent HLA finding in the published literature. A consistent association between HPV16 non-European variants and risk of disease is also evident from published work. These findings are discussed. Gaps in our understanding and future research needs are also discussed.

Host genetic control of HPV 16 titer in carcinoma in situ of the cervix uteri

Cervical cancer is strongly associated with infection by oncogenic forms of human papillomavirus (HPV). Although most women are able to clear an HPV infection, some develop persistent infections that may lead to cancer. The determinants of persistent infection are largely unknown. We have previously shown that women developing carcinoma in situ of the cervix uteri have higher titers of HPV 16 long before development of cervical neoplasia, indicating that the immune response to HPV is important in determining the outcome of an infection. The HLA class II alleles DRB1*1501 and DQB1*0602 have previously been associated with an increased risk of HPV infection, and carriers of these alleles also tend to have more long-term infections. Together these results indicate that certain HLA alleles may affect the ability to control the HPV copy number. To evaluate this possibility, we studied the HLA class II DRB1*1501-DQB1*0602 haplotype, as well as the alleles individually, and the HPV 16 titer in 928 women from a retrospective case-control study (441 cases and 487 controls). Carriers of the haplotype DRB1*1501-DQB1*0602 allele have a significantly higher HPV 16 titer compared to noncarriers (t-test with unequal variance, p = 0.017). An association was found between the HLA haplotype carrier frequency and HPV 16 titer (Mantel-Haenszel statistics p = 0.005). To study whether titer is related to the persistency of infection, women were divided into groups with long-term and short-term infection. A strong correlation is seen between long-term infection and high viral load and between short-term infection and low viral load. These results show that host genetic factors, e.g., variation at the HLA class II loci studied, may affect the immune reaction to the virus and thereby indirectly increase the susceptibility to carcinoma in situ of the cervix uteri.

A male-specific increase in the HLA-DRB4 (DR53) frequency in high-risk and relapsed childhood ALL

Previous studies reported significant HLA-DR associations with various leukemias one of which is with HLA-DRB4 (DR53) family in male patients with childhood ALL. We have HLA-DR-typed 212 high-risk or relapsed patients with childhood (n=114) and adult (n=98) ALL and a total of 250 healthy controls (118 children, 132 adult) by PCR-SSP analysis. The members of the HLA-DRB3 (DR52) family were underrepresented in patients most significantly for HLA-DRB1*12 (P=0.0007) and HLA-DRB1*13 (P=0.0001). In childhood ALL, the protective effect of DRB3 was evident in homozygous form (P=0.001). The DRB4 marker frequency was increased in males with childhood ALL (67.4%) compared to age- and sex-matched controls (42.1%, P=0.003) and female patients (35.7%, P=0.004). Besides being a general marker for increased susceptibility to childhood ALL in males, HLA-DRB4 is over-represented in high-risk patients. These results further suggest that the HLA system is one of the components of genetic susceptibility to leukemia but mainly in childhood and in boys only.