Clinicopathological implications of human papilloma virus (HPV) L1 capsid protein immunoreactivity in HPV16-positive cervical cytology

Correlation between multi-type human papillomavirus infections and viral loads and the cervical pathological grade

Objective

To investigate the relationship between single/multiple HPV infections and cervical lesions, and the correlation between viral load and the degree of cervical lesions.

Methods

A total of 27 284 patients who underwent testing for HPV were retrospectively screened and 3728 women were enrolled who tested positive for HPV when examined by liquid‐based ThinPrep cervical smear cytology test and diagnosed by histopathology at the Shanxi Provincial People's Hospital between May 2017 and March 2019. The genotype and viral load of HPV were determined by fluorescence quantitative polymerase chain reaction. Based on the pathological grade, the cervical lesions were stratified into three groups: chronic cervicitis/cervical intraepithelial neoplasia (CIN) I; CIN II/CIN III; and cervical cancer.

Results

There were significant intergroup differences in the distribution of single and multiple HPV infections. There was a positive correlation between the viral load and cervical pathological grade when the infections were caused by HPV 16, 18, 31, 33, 51, 52, 53, and 58.

Conclusion

Multi‐type HPV infections are more likely to aggravate the degree of cervical lesions than single‐type infections. The HPV type‐dependent viral load is associated with the cervical pathological grade.

Multiple HPV infections are more likely to aggravate the cervical pathological grade. The HPV viral load is type‐dependent with regard to the cervical pathological grade.

Role of HPV genotyping in risk assessment among cytology diagnosis categories: analysis of 4562 cases with cytology-HPV cotesting and follow-up biopsies

OBJECTIVE

Human papilloma virus (HPV) detection and genotyping are increasingly used in clinical risk assessment. We aimed to analyze HPV genotyping performance in risk stratification among cytology diagnosis categories.

METHODS

Between January 1, 2015 and December 31, 2016, 4562 cases with cytology-HPV co-testing and biopsy follow-up were identified. HPV tests were performed on Cobas (n=3959) or Aptima (n=603) platforms. Of the biopsies, 669 demonstrated high-grade squamous intraepithelial lesions or worse.

RESULTS

Pooled high-risk HPV testing had high overall sensitivity (97%) but low specificity (20%) and positive predictive value (20%) for biopsy-confirmed high-grade squamous intraepithelial lesions or worse. HPV16/18 genotyping had considerably improved specificity (81%) and positive predictve value (35%) in predicting high-grade squamous intraepithelial lesions or worse, especially in atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion categories. Significantly more biopsy-confirmed high-grade squamous intraepithelial lesions or worse were detected by Aptima than Cobas testing, as measured by HPV16/18 (48% vs 33%, p<0.001), non-16/18 high-risk HPV (18% vs 13%, p=0.029), or all high-risk HPV genotypes (27% vs 19%, p<0.001). Aptima genotyping showed a significantly higher positive predictive value than Cobas genotyping for biopsy-confirmed high-grade squamous intraepithelial lesions or worse in the atypical squamous cells of undetermined significance category (47% vs 23%, p<0.05).

CONCLUSIONS

HPV genotyping was sensitive for biopsy-confirmed high-grade squamous intraepithelial lesions or worse in all cytologic categories, and is particularly valuable in risk evaluation for women with atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesions. The triaging role was greatly diminished in high-risk lesions (atypical glandular cells, atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesions and high-grade squamous intraepithelial lesions) due to low specificity and positive predictive value. Aptima performance in risk management was superior to Cobas, with significantly higher positive predictive value for biopsy-confirmed high-grade squamous intraepithelial lesions or worse. Our results highlight the importance of careful data interpretation from studies using different HPV testing methods and the need to incorporate HPV E6/E7-mRNA testing into management guidelines.

Utility of human papillomavirus L1 capsid protein and HPV test as prognostic markers for cervical intraepithelial neoplasia 2+ in women with persistent ASCUS /LSIL cervical cytology

Objective: Efficient and highly predictive biomarkers reflecting the prognosis of persistent atypical squamous cells of unknown significance(ASCUS) and low grade squamous intraepithelial lesion(LSIL)s are unavailable and need to be developed urgently. We aimed to develop a predictive model for diagnosis of cervical intraepithelial neoplasia(CIN)2+ by analyzing the immunocytochemical expression of the HPV L1 capsid protein in patients with persistent ASCUS and LSIL with a high risk of HPV infection. Methods: Cervical cytology samples comprising (70 ASCUS and 215 LSIL Pap smears) were analyzed. Immunocytochemical identification of the HPV L1 capsid protein in cervical cytology samples was performed. Expression levels of HPV L1 capsid protein in cervical cytology samples were measured, and the correlation between HPV L1 expression and cervical pathologic diagnosis was evaluated. The risk for CIN2+ was calculated using the results of immunocytochemistry and the HPV DNA test. Results: Negative results for HPV L1 immunochemistry test were more frequently observed in CIN2+, and expression of the HPV L1 capsid protein was higher in CIN1 or cervicitis (Fisher's exact test, p<0.05). Diagnosis rates for CIN2+ were highest for the combination of HPV L1 capsid protein immunocytochemistry, cytology and HPV test when compared with other combinations (Akaike information criterion (AIC): 191.7, Schwarz criterion(SC): 206.3, p<0.001). Conclusion: Absence of HPV L1 capsid expression and presence of HPV type 16 or 18 infection are reliable predictors of progression to CIN2+ in patients showing persistent ASCUS and LSIL.

Human papillomaviruses' proteins with clinical utility

Cervical cancer, the fourth leading cause of cancer-associated deaths among women worldwide, is associated with human papilloma virus (HPV) infection. Despite the prophylactic HPV vaccination and the implementation of cervical and HPV-based screening programs, a significant increase in cervical cancer incidence is estimated by the year 2020. Thus, further development of diagnostic tools that allow detection and risk assesment in genital HPV infection is necessary. A special interest is focused on the HPV viral proteins whose expression might be of use either as primary screening tool or in conjunction with other markers (cellular proteins, HPV DNA, PAP test).

E2/E6 ratio and L1 immunoreactivity as biomarkers to determine HPV16-positive high-grade squamous intraepithelial lesions (CIN2 and 3) and cervical squamous cell carcinoma

Objective

Human papillomavirus (HPV) 16 is the most carcinogenic HPV genotype. We investigated if HPV16 L1 capsid protein and E2/E6 ratio, evaluated by cervical cytology, may be used as biomarkers of ≥cervical intraepithelial neoplasia (CIN) 2 lesions.

Methods

Cervical specimens were obtained from 226 patients with HPV16 single infection. Using cytology specimen, L1 capsid protein and E2/E6 ratio were detected and the results were compared with those of the conventional histologic analysis of cervical tissues (CIN1–3 and squamous cell carcinoma [SCC]) to evaluate the association.

Results

The L1 positivity of CIN2/3 was significantly lower than that of normal cervical tissue (p<0.001) and SCC demonstrated significantly lower L1 positivity than CIN1 (p<0.001). The mean E2/E6 ratios of specimens graded as SCC (0.356) and CIN2/3 (0.483) were significantly lower than those of specimens graded as CIN1 (0.786) and normal (0.793) (p<0.05). We observed that area under the receiver operating characteristic curve (AUC) for E2/E6 ratio (0.844; 95% confidence interval [CI]=0.793–0.895) was higher than that for L1 immunochemistry (0.636; 95% CI=0.562–0.711). A combination of E2/E6 ratio and L1 immunocytochemistry analyses showed the highest AUC (0.871; 95% CI=0.826–0.917) for the prediction of ≥CIN2 lesions.

Conclusion

To our knowledge, this is the first study to validate HPV L1 capsid protein expression and decreased HPV E2/E6 ratio as valuable predictive markers of ≥CIN2 cervical lesions. Cervical cytology may be analyzed longitudinally on an outpatient basis with noninvasive procedures as against invasive conventional histologic analysis.

Quantitative methylation analysis of human papillomavirus 16L1 gene reveals potential biomarker for cervical cancer progression

Human papillomavirus 16 is the most prevalent type found in cervical cancer worldwide, accounting for >50% of all cases. Quantitative methylation analysis of human papillomavirus 16L1 gene within 5' (CpGs 5600, 5606, 5609, 5615) and 3' (7136 and 7145) regions to determine potential biomarker for cervical cancer progression was performed in exfoliated cervical cells collected from 101 Thai women of precancerous and cancerous lesions. Intermediate to high methylation levels (>20%) were detected in HPV16 5'L1 regions especially CpG 5600 of all cancerous (100%) and 50% of CIN3 samples, whereas normal/CIN1 samples (80%) showed methylation levels <20%. Our results indicate the potential use of HPV 16L1 gene methylation at specific site as a biomarker for prognostic cervical cancer screening, however, suitable cutoff should be further evaluated in a larger sample size.

Effect of human papillomavirus infection on the immune system and its role in the course of cervical cancer

Human papillomavirus (HPV) is widely known as a cause of cervical intraepithelial neoplasia (CIN) and cervical cancer. The mechanisms involved have been studied by numerous studies. The integration of the virus genome into the host cells results in the abnormal regulation of cell cycle control. HPV can also induce immune evasion of the infected cells, which enable the virus to be undetectable for long periods of time. The induction of immunotolerance of the host's immune system by the persistent infection of HPV is one of the most important mechanisms for cervical lesions. The present review elaborates on the roles of several types of immune cells, such as macrophages and natural killer cells, which are classified as innate immune cells, and dendritic cells (DCs), cluster of differentiation (CD)4⁺/CD8⁺ T cells and regulatory T cells, which are classified as adaptive immune cells. HPV infection could effect the differentiation of these immune cells in a unique way, resulting in the host's immune tolerance to the infection. The immune system modifications induced by HPV infection include tumor-associated macrophage differentiation, a compromised cellular immune response, an abnormal imbalance between type 1 T-helper cells (Th1) and Th2 cells, regulatory T cell infiltration, and downregulated DC activation and maturation. To date, numerous types of preventative vaccines have been created to slow down carcinogenesis. Immune response activation-based therapeutic vaccine is becoming more and more attractive for the treatment of HPV-associated diseases.

Observations on the expression of human papillomavirus major capsid protein in HeLa cells

Background

The goal of this study was to identify the nature of the inclusion bodies that have been found in HeLa cells (cervical cancer immortal cell line) by electron microscope and to determine whether the major capsid protein (L1) of human papillomavirus (HPV) can be expressed in HPV-positive uterine cervix cancer cells.

Methods

HPV L1 protein expression in HeLa cells was detected with anti-HPV L1 multivalent mice monoclonal antibody and rabbit polyclonal anti-HPV L1 antibody by ELISA, light microscope immunohistochemistry, electron microscope immunocytochemistry and Western blotting assays. Reverse transcriptional PCR (RT-PCR) was performed to detect the transcription of L1 mRNA in HeLa cells. The immortalized human keratinocyte HeCat was used as the negative control.

Results

HPV L1 proteins reacted positively in the lysate of HeLa cells by ELISA assays. HRP labeled light microscope immunohistochemistry assay showed that there was a strong HPV L1 positive reaction in HeLa cells. Under the electron microscope, irregular shaped inclusion bodies, assembled by many small and uniform granules, had been observed in the cytoplasm of some HeLa cells. These granules could be labeled by the colloidal gold carried by HPV L1 antibody. The Western blotting assay showed that there was a L1 reaction strap at 80–85 kDa in the HeLa cell lysates, hence demonstrating the existence of HPV18 L1 in HeLa cells. RT-PCR assay showed that the L1 mRNA was transcribed in HeLa cells.

Conclusions

The inclusion bodies found in the cytoplasm of HeLa cells are composed of HPV18 L1 protein. Since HeLa cell line is a type of cervical cancer cells, this implies that HeLa cells have the ability to express HPV L1 proteins.

RNA epigenetics

Mammalian messenger RNA (mRNA) and long noncoding RNA (lncRNA) contain tens of thousands of posttranscriptional chemical modifications. Among these, the N(6)-methyl-adenosine (m(6)A) modification is the most abundant and can be removed by specific mammalian enzymes. m(6)A modification is recognized by families of RNA binding proteins that affect many aspects of mRNA function. mRNA/lncRNA modification represents another layer of epigenetic regulation of gene expression, analogous to DNA methylation and histone modification.