Occurrence of human papillomavirus in pterygia

The role of HPV in the etiopathogenesis of pterygium and the relationship with recurrence

PURPOSE

The primary aim of this study was to determine the prevalence of HPV in pterygium with polymerase chain reaction (PCR) testing and to investigate the relationship with clinicopathological factors. A secondary aim was to evaluate the relationship between HPV and the recurrence of pterygium.

METHODS

The study included 60 patients. PCR analysis was used to determine the presence of HPV. All the patients were followed up in respect of the development of recurrence. Analyses were performed of patient age, pterygium site, specimen and pterygium size, histopathological findings, HPV status, operation technique and postoperative follow-up findings. In the HPV-positive patients, the relationship between HPV subtypes and other factors was evaluated. To determine the risk factors affecting recurrence rates, multivariate Cox regression analysis was applied subsequent to univariate analysis. In the Cox regression model, HPV status, age, sex, specimen size, size and site of pterygium were included among factors that may affect recurrences rates.

RESULTS

Of the total 60 patients, the HPV-PCR test result could not be analysed in 14 because of an insufficient sample. Of the 46 patients with sufficient material for HPV-PCR analysis, the HPV-PCR result was positive in 15 (32.6%). The HPV subtype most often determined was type 16. No statistically significant relationship was determined between HPV positivity and HPV subtype and age or sex. Recurrence was determined in 10% of all the patients. Of the cases determined with recurrence, 66.7% were HPV positive. According to Kaplan-Meier analysis, the recurrence rates in HPV-positive and HPV-negative patients were 26.7% and 6.5%, respectively. A statistically significant difference was found between two groups in terms of recurrence rates (p: 0.046). According to the results of multivariate Cox regression analysis, though not statistically significant, the risk of recurrence was increased 6.18 times in HPV-positive patients with pterygium compared to HPV-negative ones.

CONCLUSION

HPV infection may have a role in the development of pterygium and recurrence, but may not be sufficient alone. HPV probably has a role in the development of pterygium by acting together with several co-factors in the multi-stage process.

Human papilloma virus presence and its physical status in primary pterygium

Pterygium is one of the most frequent pathologies in ophthalmology, and is a benign, overgrowth of fibrovascular tissue, often with a wing-like appearance, from the conjunctiva over the cornea. It is composed of an epithelium and highly vascular, sub-epithelial, loose connective tissue. There is much debate surround the pathogenesis of pterygium and a number of theories have been put forward including genetic instability, cellular proliferation, inflammatory influence, and degeneration of connective tissue, angiogenesis, aberrant apoptosis and viral infection. At present, the involvement of human papillomavirus (HPV) in the genesis of pterygium is controversial, as have reported that HPV is present in 58% of cases, while others have failed to detect HPV in pterygium. In this study, we evaluated the presence and viral genotype of HPV DNA in pterygia and healthy conjunctiva sample, and virus integration into the cellular genome. Forty primary pterygia samples and 12 healthy conjunctiva samples were analyzed to HPV DNA presence by polymerase chain reaction, using MY09/MY11 primers of HPV-L1 gene. Viral genotype was identified by DNA sequence analysis of this amplicon. HPV integration into the cellular genome was analyzed by western blot detecting HPV-L1 capsid protein. Presence of HPV was observed in 19 of the 40 pterygia samples. In contrast, healthy conjunctiva samples were negative. To determine virus type, sequence analyses were performed. Interestingly, 11 out of the 19-pterygium samples were identified as HPV-11 type, meanwhile, the remaining 8 pterygium samples were identified as HPV-18. HPV-L1 capsid protein were found only in 3 out of the 10 samples studied. In conclusion, our study identified the presence of HPV DNA exclusively in pterygium samples and described HPV-11 and -18 genotypes. Our results suggest that HPV may be involved in the pathogenesis of pterygium. On the other hand, the expression of the L1-HPV protein suggests viral integration into the cellular genome.

Association between HPV detection in swab samples and tissue specimens and ophthalmic pterygium recurrence

PURPOSE

To investigate the presence of HPV on the ocular surface after surgical excision of HPV infected pterygia and the possible correlation of HPV with pterygium postoperative recurrence.

MATERIALS AND METHODS

Both exfoliative pterygium swab samples and respective tissue specimens were received and analyzed with real-time PCR for the detection of HPV-infected pterygia. In addition, swab samples from patients that had HPV-infected pterygia with no recurrence after 1 year of follow-up, as well as swab samples from patients with healthy conjunctiva, were analyzed.

RESULTS

Forty eyes with pterygium of 40 patients and 40 eyes with normal conjunctiva were included in the study. HPV virus was detected in the tissue specimens of 11 patients (27.5%) and in the swabs of 9 patients (22.5%). The HPV subtypes detected were 33, 39, 45, 56, 59, 66, and 68. The swab test had sensitivity of 81.82% and 100% specificity. In 15 (43%) patients, a bare sclera technique was used for pterygium removal and eleven of these patients showed recurrence of the disease. Surgical excision with use of autologous conjunctival graft was performed in twenty patients and five of them had recurrence. Patients with recurrent disease were 12.41 times more likely to have an HPV-infected pterygium (p = 0.031). Furthermore, from the 11 HPV positive patients, six had no recurrence, 1 year after surgery. In five of them, a swab sample was taken from the site of the surgical excision 1 year after surgery and real-time PCR was negative for HPV presence.

CONCLUSION

Persistence of HPV infection seems to be correlated with postoperative pterygium recurrence. Further investigation with the use of the minimally invasive proposed swab technique may contribute in the understanding of pterygium pathogenesis and in the development of a more efficient treatment planning.

Prevalence of Human Papillomavirus Genotypes in Pterygia from Thai Individuals

Purpose: Pterygium, a common ocular growth, has an unknown pathogenesis and aetiology. Environmental factors such as ultraviolet light, genetic factors and viral infections may be implicated in the development of pterygia. Human papillomavirus (HPV), an oncogenic virus, has previous been detected in individuals with pterygia. The aim of this study was to assess the prevalence of HPV genotypes in pterygia from Thai individuals.Methods: DNA was extracted from 389 pterygia. HPV was detected by nested PCR and HPV genotyping was conducted using reverse hybridization. The DNA sequences of HPV-L1 genes were analyzed.Results: HPV was detected in only 6.8% (25/389) of pterygia from Thai individuals. The majority (16/25, 64%) of strains were genotyped as HPV-16 and the remainder (9/25, 36%) could not be typed. Four pterygia showed evidence of coinfection by HPV-16 and either HPV-18 (2/25, 8%) or HPV-58 (2/25, 8%). Nine of 11 samples showed the same HPV-16 L1 gene sequence that was identical to a HPV-16 reference sequence in GenBank. The remaining two samples each bore silent single nucleotide mutations (T1078G and T1081A) that did not result in amino acid changes.Conclusion: HPV, especially HPV-16, may be one of the pathogens causing pterygia in Thai individuals. Genotyping data suggested that HPV-16 from pterygia may be similar in sequence to HPV-16 causing cervical cancer.

Lack of HPV in pterygium with no evidence of autoinoculation and the role of cytokines in pterygium with dry eye

This study evaluated human papillomavirus's (HPV) role in pterygium pathogenesis, its autoinoculation from genitalia to ocular surface, potential cytokines involved, and crosstalk cytokines between pterygium and dry eye (DE). This cross-sectional study enrolled 25 healthy controls (HCs) and 116 pterygium patients. Four subgroups of pterygium and DE were used in cytokine evaluations. Conjunctival and pterygium swabs and first-void urine samples (i.e., genitalia samples) were collected for HPV DNA detection using real-time polymerase chain reaction. Tear cytokines interleukin (IL)-6, IL-18, and vascular endothelial growth factor (VEGF) in tears were evaluated. No HPV DNA was detected in conjunctival or pterygium swabs. No association was found between HPV DNA in urine samples and that from conjunctival or pterygium swabs. Tear VEGF levels were significantly higher in pterygium patients than in HCs, with no markedly different levels between primary and recurrent pterygia. Tear IL-6, IL-18, and tear VEGF were significantly higher in participants with DE, regardless of pterygium status. In conclusion, HPV infection was not a pathogenic factor of pterygia. The hypothesis of HPV transmitting from the genitals to ocular surfaces was nullified. Tear VEGF was involved in both pterygia and DE, whereas tear IL-6 and IL-18 played roles only in DE.

Ocular Human Papillomavirus Infections

CONTEXT

- Human papillomavirus (HPV) has a well-known role in the pathogenesis of squamous cell carcinoma and precursor lesions of the cervix, anogenital region, and head and neck, but its role in the development of squamous neoplasms of the eye, particularly the conjunctiva, remains unclear.

OBJECTIVE

- To review recent evidence implicating HPV in the pathophysiology of ocular lesions.

DATA SOURCES

- Published articles obtained from a PubMed search of the English literature were the primary sources for this review.

CONCLUSIONS

- The low-risk HPV types 6 and 11 appear to play a role in the development of at least a subset of conjunctival squamous papillomas. The role of HPV in the pathogenesis of pterygium and ocular surface squamous neoplasia is less well defined. There is evidence to suggest that HPV may be a cofactor in the development of these lesions, acting in concert with ultraviolet radiation and/or human immunodeficiency virus infection in a subgroup of cases.

Human papillomavirus infection and ocular surface disease (Review)

Human papillomavirus (HPV) infection has been implicated as a primary cause of lesions in the anogenital region, skin, oropharynx and respiratory tract. Additionally, the role of HPV in the pathogenesis of ocular surface disease has also been extensively studied. Conjunctival papilloma development has been strongly associated with the HPV infection of certain subtypes. On the other hand, the role of HPV in conjunctival pterygium, conjunctival intraepithelial neoplasia (CIN) and ocular surface squamous neoplasia (OSSN) remains controversial. Genetic predisposition and environmental factor is important in HPV hosts as regards the pathogenesis of ocular surface disease. Several studies have indicate a synergic role of HPV with ultraviolet radiation in pterygium establishment. A higher recurrence risk rate and more aggressive disease of ophthalmic pterygium is observed in cases of HPV infection. The purpose of this review was to provide a systematic review of the literature and to assist in a better understanding of the role of HPV in ocular surface disease.

Identification of human papillomavirus in pterygium

PURPOSE

The purpose of this study was to evaluate the involvement of human papillomavirus in the pathogenesis of primary and recurrent pterygium in northern Israel.

METHODS

A retrospective study examined 100 randomly chosen pterygium specimens with solar elastosis, from 100 patients who underwent pterygium surgery during 2012-2013 at the Emek Medical Center. All the specimens were analysed for evidence of human papillomavirus infection by immunohistochemistry.

RESULTS

Human papillomavirus was not detected in any of the 100 pterygia samples by immunohistochemistry. These used samples were taken from 100 patients with mean age of 51.5 years and a primary: recurrent ratio of 8.09:1.

CONCLUSION

We conclude from our study that human papillomavirus infection does not appear to be an important pathogenic factor of pterygium in Israel.

Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi-ethnic patients in the Malay Peninsula

PURPOSE

The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula.

METHODS

DNA was extracted from 45 specimens of freshly obtained primary and recurrent pterygia from patients and from 11 normal conjunctival swabs from volunteers with no ocular surface lesion as control. The presence of HPV DNA was detected by nested PCR. PCR-positive samples were subjected to DNA sequencing to determine the HPV genotypes. Real-time PCR with HPV16 and HPV18 type-specific TaqMan probes was employed to determine the viral DNA copy number.

RESULTS

Of 45 pterygia samples with acceptable DNA quality, 29 (64.4%) were positive for HPV DNA, whereas all the normal conjunctiva swabs were HPV negative. Type 18 was the most prevalent (41.4% of positive samples) genotype followed by type 16 (27.6%). There was one case each of the less common HPV58 and HPV59. Seven of the samples harboured mixed infections of both HPV16 and HPV18. All the four known recurrent pterygia samples were HPV-positive, whereas the sole early-stage pterygium sample in the study was HPV-negative. There was no significant association between HPV-positive status with gender or age. A high proportion of patients from the Indian ethnic group (five of six) were HPV-positive, whereas the Malay patients were found to have higher HPV positivity than the Chinese. The viral load of HPV18 samples ranged between 2 × 10(2) and 3 × 10(4) copies per μg, whereas the viral load of HPV16 specimen was 4 × 10(1) to 10(2) copies per μg.

CONCLUSION

This report describes for the first time the quantitative measurement of HPV viral DNA for pterygium samples. The high prevalence of oncogenic HPVs in our samples suggests a possible role for HPV in the pathogenesis of pterygia. Moreover, the relatively low HPV viral load is concordant with the premalignant nature of this ocular condition.

Genomic diversity of human papillomaviruses (HPV) and clinical implications: an overview in adulthood and childhood

During the last years, several researchers have highlighted the importance of characterizing more than one genomic region in order to detect recombination and classify variants of human papillomaviruses (HPVs) properly. HPVs variants differ in their biological, molecular and chemical properties. Therefore, this genomic diversity can present differences in the natural history and pathogenicity of HPVs. Different 'high-risk' HPVs variants of the genotypes HPV 16 and 18 can confer varied risks of viral persistence in the human cervix and influence HPVs progression to cervical cancer. Moreover, different 'low-risk' HPVs variants of the genotypes HPV 6 and 11 can play a unique role in the development of anogenital and cutaneous warts, recurrent respiratory papillomatosis (RRP) and ophthalmic pterygium. In future, the precise impact of genomic HPVs diversity to the clinical course of HPVs-associated diseases as well as to the efficacy of the current HPVs vaccines remains to be elucidated.

Progress in the pathogenesis of pterygium

Pterygium is a type of benign uncontrolled growth of the conjunctive tissue that lays over the sclera. It can significantly alter visual function in advanced cases and become inflamed, leading to redness and irritation in the area. Although the exact etiology of pterygium remains uncertain, recent advances have provided important insight into the pathogenesis of pterygium. These studies indicate that tumor suppressor gene p53 and other genes associated with DNA repair, cell proliferation, migration and angiogenesis are critical for the development of pterygium. In addition, Human papillomavirus infection has been shown to be a risk factor in some populations. In this article, the current understanding of the pathogenesis of pterygium is reviewed.

Viral involvement in the pathogenesis and clinical features of ophthalmic pterygium (Review)

Pterygium is a potentially vision-threatening fibrovascular lesion originating from the conjunctiva that often extends on the corneal surface. Although it has been extensively studied, its pathogenesis has yet to be fully elucidated. Recent evidence on molecular genetic abnormalities in pterygium suggested neoplastic changes of limbal stem cells potentially associated with exposure to ultraviolet (UV) light. Human papillomavirus (HPV) is an oncogenic virus, associated with squamo-proliferative lesions of the anogenital region, skin and oropharynx. Several studies have shown HPV involvement in the pathogenesis of conjunctival neoplastic lesions, including papilloma and squamous cell carcinoma. The involvement of HPV as a co-factor in the pathogenesis of pterygium, although suggested by several studies using PCR and immunohistochemical techniques, remains controversial. Moreover, a marked variation in the prevalence of HPV in ophthalmic pterygium has been reported by different studies. Ethnic susceptibility and methodological differences in the detection of HPV may account for this variation. Surgical excision, often using sophisticated techniques, is the standard current method of therapy for pterygium. However, recurrences are frequent and recurrent lesions tend to be more aggressive. If indeed HPV is involved in pterygium pathogenesis or recurrence, anti-viral medications or vaccination may be new options in pterygium therapy.

Differential presence of Papillomavirus variants in cervical cancer: an analysis for HPV33, HPV45 and HPV58

BACKGROUND

Certain human papillomaviruses (HPVs) are the causative agents of cervical carcinomas in humans. The identification of the link between infection and cancer has resulted in the successful establishment of clinical strategies such as screening or vaccination programs, aiming to prevent this pathology. More than 150 different HPVs have been described and classified and the large majority of them are not related to cancer. The genus Alphapapillomavirus encompasses many PVs, some of which are identified in humans as oncogenic, according to the epidemiological connection between infection and cervical cancer. Variants of some of these "high-risk" HPVs may have an increased involvement in cervical cancer, although definitive data are still wanting. The aim of the present work was to analyze the presence of HPV33, HPV45 and HPV58 variants in cases of cervical cancer.

METHODS

Samples from cervical lesions in the context of different cervical cancer surveys were analyzed for presence of HPV DNA. Samples positive for HPV33, HPV45 or HPV58 DNA were selected and the E6/E7 genes were amplified and sequenced. The phylogenetic relationships of these sequences were inferred using an evolutionary placement algorithm and accordingly classified at the variant level.

RESULTS

All viral E6/E7 sequences were successfully placed in the classification schemes of the corresponding viruses. For HPV33 (n=23), 45 (n=61) or 58 (n=29), the distribution of variants found in cases of cervical cancer is not a random sample of the corresponding diversity. In all three HPVs, the respective A variants were more prevalent in the viral DNA-positive cases of cervical cancer analyzed. This is the first study trying to discern the phylogenetic connection between variants of the oncogenic HPV33, 45 and 58, and squamous cell carcinoma of the cervix.

Association of human papilloma virus with pterygia and ocular-surface squamous neoplasia

There are more microorganisms that colonize the human body than resident cells; some are commensal whereas others are pathogenic. Pathogenic microorganisms are sensed by the innate or adaptive immune system, an immune response is initiated, and the infection is often cleared. Some microorganisms have developed strategies to evade immune defenses, ensuring their long-term survival with potentially devastating consequences for the host. Approximately 18% of all cancers can be attributed to infective agents; the most common being Helicobacter pylori, Human papilloma virus (HPV) and Hepatitis B and C virus in causing stomach, cervical and liver carcinoma, respectively. This review focuses on whether HPV infection is necessary for initiating pterygia, a common benign condition and ocular-surface squamous neoplasia (OSSN), a rare disease with metastatic potential. The search engine PubMed was used to identify articles from the literature related to HPV and pterygium or conjunctival neoplasia. From 34 investigations that studied HPV in pterygia and OSSN, a prevalence rate of 18.6% (136/731) and 33.8% (144/426), respectively, was recorded. The variation in HPV prevalence (0-100%) for both disease groups may have arisen from study-design faults and the techniques used to identify the virus. Overall, the data suggest that HPV is not necessary for initiating either condition but may be a co-factor in susceptible hosts. Currently, over 60 million people worldwide have been immunized with HPV vaccines, but any effect on pterygium and OSSN development may not be known for some time as these lesions can evolve over decades or occur in older individuals.

Expression of double strand DNA breaks repair genes in pterygium

PURPOSE

The alteration in the expression of some genes and proteins responsible for chosen DNA repair pathways in pterygium pathogenesis were studied. This study was focused on the examination of the expression of genes and RAD50 protein taking part in homologous recombination.

METHODS

Peripheral blood lymphocytes, samples of pterygium tissue, samples of conjunctiva of patients suffering from pterygium as well as peripheral blood lymphocytes and conjunctiva of patients from the control group were examined. In order to identify genes products from RNA, Ribonuclease Protection Assai method was applied. LIM15, RAD50, RAD54, RAD52, MRE11, XRCC2, XRCC3, RAD51, RAD51B, RAD51C, RAD51D genes transcripts were detected. Expression of RAD50 protein was analyzed immunohistochemically.

RESULTS

Peripheral blood lymphocytes analyses revealed lower level of RAD50 gene expression in the pterygium patients compared to the control group and the increased expression of XRCC2, XRCC3 and RAD51 genes in patients with pterygium, who declared the recurrence of the lesion in comparison to the patients with primary pterygium. Lower expression of the RAD54 gene in pterygium tissue comparing to conjunctiva from the eyes with pterygium was found. An expression of RAD50 gene in the conjunctiva originating from eyes with pterygium in comparison to the conjunctiva of control group was shown to be considerably higher. Expression of RAD50 protein in pterygium squamous epithelial cells was significantly higher than in conjunctiva from control group.

CONCLUSION

There may exist a relationship between pterygium pathogenesis and damages of double strand DNA, however, the elucidation of its exact nature needs further study.