Vascular endothelial growth factor gene 460 polymorphism is associated with pterygium formation in female patients

Thrombospondin 1 polymorphism associated with decreased expression and increased risk of pterygium

PURPOSE

To assess the potential association of a thrombospondin 1 gene (THBS1) single-nucleotide polymorphism (rs1478604) with thrombospondin 1 (TSP-1) mRNA expression, as well as the risk of pterygium, in a pilot study.

METHODS

DNA and RNA were isolated from peripheral blood samples collected from normal volunteer subjects (n = 39). In addition, DNA was isolated from conjunctival tissue samples collected during pterygium excision surgeries (n = 42). Relative expression of TSP-1 mRNA was measured by quantitative RT-PCR, and rs1478604 genotype was determined using a TaqMan SNP genotyping assay. Genotype frequencies were compared with mRNA expression and between pterygium samples and normal controls.

RESULTS

Expression of TSP-1 mRNA was significantly lower in the peripheral blood of normal subjects who were homozygous for the C allele of rs1478604 (CC) compared to TT and CT genotypes (p = 0.004). When we compared rs1478604 genotypes between normal and pterygium patients, we found that the CC genotype was also associated with an increased risk of pterygium compared to TT (odds ratio (OR) = 5.39, 95% CI [1.26-22.99], p = 0.028), CT (OR = 7.86, 95% CI [1.92-32.17], p = 0.003), and combined CT and TT genotypes (OR = 6.67; 95% CI = [1.75-25.37]; p = 0.003).

CONCLUSIONS

We found that the C allele of rs1478604 was associated with both lower TSP-1 expression and higher risk of pterygium, possibly implicating TSP-1 in the pathogenesis of pterygium.

The Association of MMP7 Genotype With Pterygium

BACKGROUND/AIM

In literature, few studies have examined the diagnostic or prognostic potential of matrix metalloproteinases (MMP) in pterygium, whose formation and progression are closely related to imbalance in the extracellular microenvironment. In this study, we investigated the contribution of MMP7 promoter (A-181G and C-153T) polymorphic genotypes to pterygium risk.

MATERIALS AND METHODS

A total of 134 cases and 268 controls were collected and their MMP7 genotypes at A-181G and C-153T were examined by polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The AA, AG and GG genotypes at MMP7 promoter A-181G were non-significantly differentially distributed between the two groups at 85.8, 11.2 and 3.0%, respectively, in pterygium cases and 88.4, 9.7 and 1.9% in controls, respectively (p for trend=0.6822). There was no polymorphic genotype for MMP7 C-153T among our Taiwanese cohort.

CONCLUSION

A-181G and C-153T genotypes at MMP7 do not have a direct role in determining Taiwanese susceptibility to pterygium.

Low-Dose Mitomycin C Decreases the Postoperative Recurrence Rate of Pterygium by Perturbing NLRP3 Inflammatory Signalling Pathway and Suppressing the Expression of Inflammatory Factors

A pterygium is generally believed to be a chronic inflammatory lesion caused by external stimuli that develops from the conjunctiva and grows onto the cornea. Simple bare sclera excision is the most commonly used method to treat pterygium. However, the high postoperative recurrence rate of pterygium remains a persistent challenge. Mitomycin C (MMC) is an antineoplastic antibiotic that inhibits DNA, RNA, and protein synthesis. In recent years, although MMC has proven useful for the treatment of pterygium, its application has been controversial because of its clear toxicity and the possibility of ocular complications. In the current study, we prospectively recruited patients to receive or not receive a local injection of MMC (0.4 mg/ml). Follow-up was conducted with the patients to determine the postoperative recurrence rate of pterygium and/or to observe any ocular complications. The remarkable results demonstrated that MMC can decrease the postoperative recurrence rate of pterygium without leading to serious eye complications. Further results indicated that MMC can inhibit the activation of the NLRP3 inflammatory signalling pathway and thus downregulate the expression of downstream molecules, including IL-18 and IL-1β. MMC also reduced the expression of inflammatory factors TGF-β1, VEGF, and IL-6. In addition to influencing these factors, MMC suppressed neovascularization and the proliferation of corneal fibroblasts to effectively reduce the recurrence rate of pterygium. Taken together, our results provide a theoretical basis for the development of prevention and treatment strategies for pterygium and suggest that MMC is highly effective as an adjunctive treatment after excision of primary pterygia.

VEGF mRNA assessment in human pterygium: a new 'scope' for a future hope

PURPOSE

The lack of powerful evidence to support the efficacy of anti-vascular endothelial growth factor (VEGF) therapy in human pterygium can be attributed to incomplete VEGF expression assessment by restrictive use of immunohistochemistry only and failure to use the molecular methods able to confirm immunohistochemical findings. By adding at least one more sensitive method to assess human pterygium VEGF expression, a more accurate selection of patients for bevacizumab therapy could be done and this would improve the efficacy of anti-VEGF therapy in human pterygium.

METHODS

We assessed VEGF mRNA amplification on paraffin-embedded specimens by applying the RNAscope method for the first time in human pterygium, an in situ hybridization-based technique able to detect VEGF mRNA as a single gene copy on paraffin-embedded samples.

RESULTS

Heterogeneous VEGF mRNA distribution and amplification inside the epithelial compartment of human pterygium were observed. Despite previous reports concerning the immunohistochemical expression of VEGF in the human pterygium fibrovascular compartment, no stromal components were characterized by VEGF mRNA amplification assessed by in situ hybridization in our study. A higher amplification score was observed in epithelium from recurrent pterygium, especially located in the basal and suprabasal epithelial cells.

CONCLUSIONS

Based on our findings we consider that in situ hybridization assessment of VEGF for human pterygium specimens can be a useful tool for reconsidering the selection of pterygium patients to be enrolled in anti-VEGF therapy.

Vascular endothelial growth factor gene polymorphism and protein expression in the pathogenesis of pterygium

BACKGROUND AND AIMS

Vascular endothelial growth factor (VEGF) gene expression has been linked to cancer progression. Here we hypothesise that the polymorphism and protein expression of VEGF are correlated with the pathogenesis and therapy response of pterygium.

METHODS

60 pterygial and 121 normal conjunctival samples were collected to determine the genotypes and protein expression of VEGF. Primary pterygium cells (PECs) were used to confirm the effect of the VEGF polymorphism on the angiogenesis of pterygium.

RESULTS

48 (83.3%) pterygial specimens tested positive for VEGF protein expression, which was significantly higher than in the control groups (16.7%, p<0.0001). The frequency of the 936 C>T variant, but not the -2578C>A variant, was significantly higher in the pterygium group compared with the control group. VEGF protein expression was significantly higher in the 936 C/C group than in the 936 C/T and T/T groups (p=0.001). The results of our cell model showed that PECs with the C/C genotype had a higher angiogenesis ability and higher response to the antiangiogenesis drug bevacizumab than cells with the C/T and T/T genotypes.

CONCLUSIONS

We suggest that VEGF could be used as a target for pterygium therapy in patients with the 936C>T genotype.

Immunohistochemical detection of Hsp90 and Ki-67 in pterygium

BACKGROUND

To examine the immunohistochemical expression of heat shock protein 90 (Hsp90) and Ki-67 protein in human pterygium.

MATERIALS AND METHODS

Tissues obtained during pterygium surgery of 15 patients who underwent the bare-sclera procedure and 10 normal conjunctivae were studied. All of these pterygia were primary ones. Recurrent pterygia were excluded. Normal bulbar conjunctivas (2 x 2 mm) were obtained from the nasal region close to the limbus from patients during their cataract and retina surgeries. Immunohistochemical detection of Hsp90 and Ki67 was done using the streptavidin-biotin method in paraffin embedded tissue sections.

RESULTS

The percentage of cells stained for Hsp90 was greater for pterygium epithelium (76 ± 10.8) than for normal conjunctiva (1.4 ± 0.8). In each pterygium sample more than 60% of cells were positive. The differences in positive cells between normal and pterygium epithelium were highly significant for Hsp90 (P < 0,001).Pterygium epithelium also showed a higher percentage of cells that stained for Ki67 (10.1 ± 9.5) than for normal conjunctiva (2.1 ± 1.9). The differences in positive cells were also statistically significant for Ki67 (P < 0.01). Although there were significant differences in the majority of samples observed. It was noted that in some samples there was no difference between normal and pterygium epithelium for Ki67.

CONCLUSION

Our results indicate an abnormal expression of Hsp90 and ki-67 in pterygium samples when compared to normal conjunctiva.The finding of abnormal expression of levels of Hsp90 in pterygium samples can stimulate new research into pterygium and its recurrence.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1128478792898812.

Molecular effects of doxycycline treatment on pterygium as revealed by massive transcriptome sequencing

Pterygium is a lesion of the eye surface which involves cell proliferation, migration, angiogenesis, fibrosis, and extracellular matrix remodelling. Surgery is the only approved method to treat this disorder, but high recurrence rates are common. Recently, it has been shown in a mouse model that treatment with doxycycline resulted in reduction of the pterygium lesions. Here we study the mechanism(s) of action by which doxycycline achieves these results, using massive sequencing techniques. Surgically removed pterygia from 10 consecutive patients were set in short term culture and exposed to 0 (control), 50, 200, and 500 µg/ml doxycycline for 24 h, their mRNA was purified, reverse transcribed and sequenced through Illumina's massive sequencing protocols. Acquired data were subjected to quantile normalization and analyzed using cytoscape plugin software to explore the pathways involved. False discovery rate (FDR) methods were used to identify 332 genes which modified their expression in a dose-dependent manner upon exposure to doxycycline. The more represented cellular pathways included all mitochondrial genes, the endoplasmic reticulum stress response, integrins and extracellular matrix components, and growth factors. A high correlation was obtained when comparing ultrasequencing data with qRT-PCR and ELISA results. Doxycycline significantly modified the expression of important cellular pathways in pterygium cells, in a way which is consistent with the observed efficacy of this antibiotic to reduce pterygium lesions in a mouse model. Clinical trials are under way to demonstrate whether there is a benefit for human patients.

Anti-VEGF therapy with bevacizumab for anterior segment eye disease

PURPOSE

To review the current literature concerning the use of bevacizumab in treating neovascular disorders affecting the anterior segment ocular structures.

METHODS

The authors reviewed the literature on anti-vascular endothelial growth factor (VEGF) therapy with bevacizumab for various anterior segment neovascular disorders that was indexed in MEDLINE (up to January 2011).

RESULTS

Response to bevacizumab anti-VEGF therapy is variable, based on the amount of scarring, the chronicity and extent of corneal neovascularization, the disease process, and the medication formulation and its route of administration. Anti-VEGF agents are especially effective when administered early, before anatomical changes, such as corneal neovascularization and/or angle closure, are established. Neovascularization can recur if the ischemic or inflammatory process is not reversed, so eyes with long-standing diseases, such as autoimmune disorders that involve ongoing inflammation and VEGF production, seem to be less responsive to bevacizumab anti-VEGF therapy. For established neovascularization, combining anti-VEGF agents with the removal of established vessels may be more effective than anti-VEGF therapy alone. Subconjunctival bevacizumab may be more appropriate for focal, deep, and peripheral neovascularization, whereas diffuse superficial neovascularization with central corneal involvement may be best treated via topical application.

CONCLUSIONS

Besides the widely accepted use of bevacizumab in cancer therapy and chorioretinal neovascularization, the initial, striking, short-term response and patients' high tolerance of local bevacizumab therapy offer encouraging results for the potential role of anti-VEGF agents in treating anterior segment neovascular disorders. Controlled prospective trials are needed to establish the long-term safety, efficacy, and dosing guidelines for the use of anti-VEGF agents in anterior segment neovascularization.