Fibroblast biology in pterygia

Safety and efficacy of "hydro-fluorescein" technique in removing Tenon in pterygium surgery: a 1-year follow-up study

PURPOSE

To assess the effectiveness and safety of the "hydro-fluorescein" adjunct technique for primary pterygium removal.

DESIGN/METHODS

A non-randomized prospective study was conducted for various types of pterygium excision with superior bulbar conjunctival autograft (CAG) and fibrin glue. We introduced fluorescein staining to ensure thorough elimination of the Tenon tissue around the bare sclera area and the CAG. The primary outcome was the recurrence rate, and the secondary outcome was any complication associated with fluorescein staining.

RESULTS

Ninety-three participants with primary pterygium of Grades 1-3 were recruited and all completed follow-up for at least 1 year. No recurrence was identified during the follow-up period and no long-term adverse reactions were reported with the "hydro-fluorescein" method.

CONCLUSION

"Hydro-fluorescein" is effective and a safe adjunct in primary pterygium removal and is effective in various grades of pterygia to minimize recurrence with no adverse reaction within 1 year.

Corneal steep island formation after primary pterygium surgery

AIMS

This study aimed to report corneal steep island (CSI) formation following primary pterygium surgery and to identify preoperative pterygium morphological features that predict the likelihood of CSI.

METHODS

A total of 93 eyes from 84 subjects with primary nasal pterygium, who underwent pterygium excision combined with conjunctival-limbal autograft, were included in this retrospective longitudinal cohort study. CSI was defined using anterior segment swept-source optical coherence tomography (AS SS-OCT). Eyes were divided into two groups: those with postoperative CSI formation (Group 1) and those without postoperative CSI (Group 2). We compared postoperative anterior corneal astigmatism (ACA, in diopters [D]) and root mean square (RMS) values of anterior corneal lower-order (LoA) and higher-order aberrations (HoA) between the groups. Baseline clinical severity grades of pterygium based on the pre-established pterygium body morphology and vascularity, ACA, and AS SS-OCT-guided pterygium morphological profiles (horizontal invasion length [HIL, mm], height [μm], thickness (μm), and residual corneal thickness [RCT]/central corneal thickness [CCT] ratio [RCT/CCT]) were also compared.

RESULTS

Postoperative CSI occurred in 26 eyes (28.0%) with a maximum follow-up duration of 22.9±27.4 months. Group 1 exhibited significantly higher postoperative anterior corneal RMS LoA and HoA, as well as the RMS values of the 4th to 6th orders. Although clinical severity grades of pterygium did not differ between groups, baseline ACA was higher in Group 1 (4.56±5.49 D vs. 2.70±3.80 D, P = 0.009). HIL (4.49±0.84 mm vs. 3.77±1.29 mm, P = 0.010) was higher in Group 1, while pterygium height (930.8±84.4 μm vs. 999.3±128.0 μm, P = 0.015) and RCT/CCT ratio (1.07±0.13 vs. 1.14±0.16, P = 0.049) were lower in Group 1.

CONCLUSIONS

CSI may develop after primary pterygium surgery, particularly in patients with relatively higher preoperative ACA, longer HIL, and shorter height. Given that CSI can significantly increase both lower and higher-order aberrations, it is crucial to anticipate CSI probability and inform patients before surgery.

Distinct activation of M1 and M2 macrophages in the primary pterygium lymphangiogenesis

The precise role and innate immunological mechanisms underlying lymphangiogenesis in pterygium remain unclear. This study aimed to investigate the presence of M1 and M2 macrophages and their correlation with pro-lymphangiogenic activation and lymphatic endothelial expression in human pterygium stromal tissues. We analyzed human pterygium and subject-matched normal conjunctival tissues for the expression of these factors and conducted in vitro experiments to assess interactions between macrophages and pterygium fibroblasts. Myeloid and M1 macrophage markers were upregulated in pterygium. M1 macrophages were associated with the upregulation of pro-lymphangiogenic vascular endothelial growth factor C (Vegfc) in pterygium tissues and induced inflammatory signals in pterygium fibroblasts. In contrast, lymphatic vessel endothelial hyaluronan receptor 1 (Lyve1) expression was associated with M2 markers but not with M1 markers. Notably, the clinical severity of pterygium was inversely correlated with the expression of the M2 marker Cd163. These findings suggest that M1 and M2 macrophages play distinct roles in the pathogenesis of pterygium, with M1 macrophages enhancing lymphangiogenic stimulation and inflammatory responses, while M2 macrophages are associated with Lyve1 expression and reduced severity of pterygium. Understanding these mechanisms may advance our current understanding of lymphatic biology in pterygium.

Comparison of postoperative topical interferon-α2b versus intraoperative mitomycin C for pterygium recurrence prevention: a randomized clinical trial

PURPOSE

To evaluate the effect of postoperative interferon-alpha 2b (IFN-α2b) ophthalmic drops versus intraoperative mitomycin-c (MMC) on preventing pterygium recurrence.

METHODS

This prospective randomized clinical trial was conducted on patients who were candidates for pterygium surgery. A total of 75 patients were included in the study from December 2021 to December 2022, of which 64 patients (one eye each) were examined and analyzed based on the inclusion criteria. Then the patients were randomly assigned to control groups, intra-operative MMC (32 patients) and the intervention group, IFN-α2b drops after the operation (32 patients). All patients underwent pterygium surgery using the rotational conjunctival flap method.

RESULTS

In terms of pterygium grading, 8 (12.5%), 25 (39.06%), and 31 (48.44%) eyes were in grades 1, 2, and 3, respectively. The average size of the pterygium was 3.6 ± 0.7 mm. The grade and size of pterygium had the same distribution in the two groups. There was no statistically significant difference between the two groups in the level of post-operative clinical inflammation. The present study showed no significant difference in complications between the two groups (p = 0.999). The recurrence rate in the control group was 9.4% (3 eyes), and 0% (no recurrence) in the intervention group (p = 0.119).

CONCLUSIONS

interferon-alpha 2b group did not show a statistically significant difference in preventing pterygium recurrence compared to the mitomycin C group. The post-surgery administration of IFN-α 2b drops can effectively prevent pterygium recurrence with a comparable and even more compelling effect than MMC during surgery.

Timing optimization for primary pterygium excision with conjunctival-limbal autograft to restore the corneal optical properties

PURPOSE

To propose the optimal value of baseline corneal astigmatism and pterygial morphological profiles for primary pterygium surgery to restore the corneal optical properties.

METHODS

We analysed 93 eyes from 84 subjects with nasal-only primary pterygium who underwent pterygium excision with conjunctival-limbal autograft and were assessed perioperatively using anterior segment swept-source optical coherence tomography (AS SS-OCT). We collected data on anterior corneal astigmatism (ACA) and root mean square (RMS) values for anterior corneal lower- (LoA) and higher-order aberrations (HoA) as corneal optical properties using AS SS-OCT. Using preoperative ACA and four pterygial morphological profiles (horizontal invasion length [HIL], height, thickness and the ratio of residual corneal thickness [RCT] to central corneal thickness [CCT]) measured in AS SS-OCT, we plotted receiver operating characteristic (ROC) curves. These curves aimed to determine cut-off values predicting a perioperative decrease exceeding 50% in ACA, RMS LoA and RMS HoA, as well as postoperative residual ACA higher than 1.25D.

RESULTS

Preoperative ACA > 1.42D (AUC = 0.934) and >3.60D (AUC = 0.946) proved most effective in identifying subjects with perioperative decrease exceeding in ACA and RMS LoA, respectively. HIL > 3.34 mm (AUC = 0.941) was most effective in distinguishing subjects with perioperative reduction exceeding 50% in RMS HoA. Preoperative ACA > 5.78D (AUC = 0.776) and HIL > 5.03 mm (AUC = 0.700) significantly distinguished subjects with postoperative residual ACA higher than 1.25D.

CONCLUSION

Optimizing the restoration of corneal astigmatism and aberrations after pterygium surgery may be facilitated by determining the optimal surgical timing based on preoperative ACA and HIL values.

Efficacy of epidermal growth factor in suppressing inflammation and proliferation in pterygial fibroblasts through interactions with microenvironmental M1 macrophages

The protein epidermal growth factor (EGF), which plays a crucial role in promoting cell proliferation and survival, has recently demonstrated potential in reducing inflammation. In this study, we examined the impact of EGF on the anti-inflammatory and anti-proliferative properties of pterygium, a prevalent hypervascular proliferative disease affecting the ocular surface. In surgically excised tissues, markers for fibrotic and inflammatory signals, including VIM, ACTA2, FAP, MMP2, VCAM1, ICAM1, CD86, IL6, and IL1B were upregulated in the pterygium body stroma compared to the normal conjunctival stroma. EGF exerted anti-inflammatory and anti-vasculogenic effects on pterygial fibroblasts when co-cultured with M1 macrophages. Moreover, exosomes derived from EGF-preconditioned M1 macrophages suppressed the heightened inflammatory and vasculogenic signals in pterygial fibroblasts induced by exosomes from M1 macrophages. Paradoxically, the proliferation of pterygial fibroblasts was inhibited by EGF in the in vitro microenvironment with M1 macrophages, despite EGF being known as a growth factor. EGF-preconditioning of M1 macrophages rescued the increased proliferation of pterygial fibroblasts induced by exosomes from M1 macrophages. In conclusion, our findings demonstrate that EGF effectively mitigates inflammation and proliferation in pterygial fibroblasts within a microenvironment containing M1 macrophages.

Facilitated Tenon-Free Conjunctival Autograft Preparation and Limited Tenon Removal Technique in Pterygium Surgery

BACKGROUND

The main complication of primary pterygium surgery is the recurrence of the pterygium. In the present study, we aimed to compare a classical technique and facilitated tenon-free conjunctival autograft preparation and a limited tenon removal technique in pterygium surgery in terms of recurrence rate, complications, and operation duration.

MATERIAL AND METHODS

This is a retrospective, comparative, observational study. Group 1 comprised 120 eyes of 115 patients who underwent pterygium excision with a new facilitated tenon-free conjunctival-limbal autograft preparation and limited tenon removal technique between May 2017 and October 2019. Group 2 comprised 117 eyes of 113 patients who underwent pterygium excision with a conventional conjunctival-limbal autograft technique between January 2016 and May 2017.

RESULTS

The mean follow-up time after surgery was 18.2 ± 5.8 months in group 1 and 19.1 ± 6.3 months in group 2 (p = 0.25). The mean operation duration was 5.54 ± 1.22 (4 - 7) minutes in group 1 and 8.23 ± 1.26 (8 - 10) minutes in group 2 (p = 0.02). Flap edema was present in 33 eyes (28.2%) in group 2 and in 11 eyes (9.16%) in group 1. Flap edema was significantly higher in group 2 (p < 0.001). At the end of the 1-year follow-up of the patients, we observed recurrence in only one (0.83%) eye in group 1 and 14 (11.96%) eyes in group 2. The recurrence rate of group 1 was significantly less than that of group 2 (p < 0.001).

CONCLUSIONS

The simplified technique of tenon-free conjunctival autograft preparation and limited tenon removal yielded better clinical outcomes without serious complications. Additionally, this technique shortened the surgical time and reduced surgeon-dependent factors.

Single-cell RNA sequencing reveals the complex cellular niche of pterygium

PURPOSE

Pterygium is a vision-threatening conjunctival fibrovascular degenerated disease with a high global prevalence up to 12 %, while no absolute pharmacotherapy has been applied in clinics. In virtue of single-cell RNA sequencing (scRNA-seq) technique, our study investigated underlying pathogeneses and potential therapeutic targets of pterygium from the cellular transcriptional level.

METHODS

A total of 45605 cells from pterygium of patients and conjunctiva of normal controls (NC) were conducted with scRNA-seq, and then analyzed via integrated analysis, pathway enrichment, pseudotime trajectory, and cell-cell communications. Besides, immunofluorescence and western blot were performed in vivo and in vitro to verify our findings.

RESULTS

In brief, 9 major cellular types were defined, according to canonical markers. Subsequently, we further determined the subgroups of each major cell lineages. Several newly identified cell sub-clusters could promote pterygium, including immuno-fibroblasts, epithelial mesenchymal transition (EMT)-epithelial cells, and activated vascular endothelial cells (activated-vEndo). Besides, we also probed the enrichment of immune cells in pterygium. Particularly, macrophages, recruited by ACKR1+activated-vEndo, might play an important role in the development of pterygium by promoting angiogenesis, immune suppression, and inflammation.

CONCLUSION

An intricate cellular niche was revealed in pterygium via scRNA-seq analysis and the interactions between macrophages and ACKR1+ activated-vEndo might be the key part in the development of pterygia.

Subconjunctival dexamethasone-assisted conjunctival autograft harvesting versus normal saline during pterygium surgery - A randomized clinical trial

PURPOSE

To evaluate the effect of subconjunctival dexamethasone compared to normal saline on conjunctival autograft harvesting in patients undergoing pterygium surgery.

METHODS

Fifty-two eyes of 52 patients who underwent pterygium excision combined with autologous conjunctival graft (CAG) using releasable suture were included in this prospective interventional study. The patients were randomized into two groups of 26 patients each. Group A consisted of patients in whom CAG was harvested using subconjunctival 0.5 ml of 0.4% dexamethasone sodium phosphate and in group B patients, normal saline was used. The patients were assessed for postoperative pain, foreign body sensation, and watering as the subjective signs of inflammation and conjunctival inflammation and lid edema as the objective signs of inflammation at 12 and 24 h postsurgery.

RESULTS

The mean age of group A and B patients was 47.69 + 13.09 and 46.00 + 10.76 years, respectively. The male:female ratio was 1.6:1 in group A and 1.1:1 in group B. The mean surgical time in group A was 243.96 ± 52.13 s and in group B was 258.08 ± 43.99 s. Postoperative pain, foreign body sensation, and watering were significantly lower in group A patients than in group B patients at both 12 and 24 h postoperatively (group A: 4.65 ± 1.33, 4.88 ± 1.73, and 3.85 ± 1.43, respectively, at 12 h; 1.89 ± 1.03, 1.69 ± 1.09, and 1.69 ± 0.97, respectively, at 24 h and group B: 6.42 ± 0.95, 6.65 ± 0.98, and 6.27 ± 1.40, respectively, at 12 h; 3.27 ± 1.43, 3.12 ± 1.25, 2.58 ± 1.14, respectively, at 24 h) ( P < 0.001). Conjunctival inflammation was significantly lower in group A at 12 h ( P < 0.05) and 24 h ( P < 0.05) after surgery compared to group B. Lid edema failed to show any significant ( P = 0.17) difference with respect to severity in both the groups at 12 and 24 h ( P = 0.699).

CONCLUSION

Subconjunctival dexamethasone decreased patient discomfort following pterygium surgery. The dexamethasone group had reduced conjunctival inflammatory signs without any notable complications.

A New Approach: Determination of the Safe Surgical Margin in Pterygium Surgery

PURPOSE

In this retrospective study, we aimed to determine the safe surgical limit for excision of pterygium tissue. Therefore, we aimed to prevent excessive or incomplete normal conjunctival tissue excision during surgery in the coming years.

METHODS

Autografted pterygium surgery was performed between January 2015 and April 2016, and the excised pterygium tissue was examined histopathologically. The files of 44 patients, who had not previously undergone any ocular surgery, who did not have an inflammatory disease and who continued to be checked for at least 1 year, were retrospectively examined. The distance (P-DSEM) from the excised pterygium tissue to the surgical excision margin was measured by a pathologist. Postoperative recurrence rates were evaluated according to this value. In this way, the clean surgical margin was determined.

RESULTS

The mean age of the participants was 44.77 ± 12.70, and the mean follow-up time was 55.61 ± 16.38 months. Recurrence developed in 5 out of 44 patients (11.4%). The average recurrence duration was 51 ± 13.87 days. Distance to the average surgical margin was 3.88 ± 0.91 mm. The surgical distances of 5 patients with recurrence were 2, 2.5, 2, 3, and 3 mm, respectively. It was determined that recurrence was less as the distance (P-DSEM) from the tissue to the surgical excision margin increased (p = 0.001).

CONCLUSIONS

We found that the recurrence rate in pterygium surgery was linked to the clean surgical margin. When planning pterygium surgery, we believe that determining the amount of tissue to be excised before surgery will reduce recurrence rates.

Impairment of autophagy promotes human conjunctival fibrosis and pterygium occurrence via enhancing the SQSTM1-NF-κB signaling pathway

Pterygium is a common ocular disease with a high recurrence rate, characterized by hyperplasia of subconjunctival fibrovascular tissue. Autophagy, an important process to maintain cellular homeostasis, participates in the pathogenic fibrosis of different organs. However, the exact role of autophagy in pterygium pathogenesis remains unknown. Here, we found that autophagic activity was decreased in human pterygium tissues compared with adjacent normal conjunctival tissues. The in vitro model of fibrosis was successfully established using human primary conjunctival fibroblasts (ConFB) treated with transforming growth factor-β1 (TGF-β1), evidenced by increased fibrotic level and strong proliferative and invasive capabilities. The autophagic activity was suppressed during TGF-β1- or ultraviolet-induced fibrosis of ConFB. Activating autophagy dramatically retarded the fibrotic progress of ConFB, while blocking autophagy exacerbated this process. Furthermore, SQSTM1, the main cargo receptor of selective autophagy, was found to significantly promote the fibrosis of ConFB through activating the PKCι-NF-κB signaling pathway. Knockdown of SQSTM1, PKCι, or p65 in ConFB delayed TGF-β1-induced fibrosis. Overexpression of SQSTM1 drastically abrogated the inhibitory effect of rapamycin or serum starvation on TGF-β1-induced fibrosis. Collectively, our data suggested that autophagy impairment of human ConFB facilitates fibrosis via activating the SQSTM1-PKCι-NF-κB signaling cascades. This work was contributory to elucidating the mechanism of autophagy underlying pterygium occurrence.

Understanding Inflammation-associated Ophthalmic Pathologies: A Novel 3D Co-culture Model of Monocyte-myofibroblast Immunomodulation

PURPOSE

Inflammation is associated with, and may be causal of, a variety of ophthalmic pathologies. These pathologies are currently difficult to model in vitro because they involve complex interactions between the innate immune system, stromal cells, and other cells that normally maintain ocular tissue homeostasis. Using transscleral drainage channel fibrosis after glaucoma surgery as an example of inflammation-associated ocular fibrosis, we have assessed a simple but novel 3D cell culture system designed to reveal the immunomodulatory impacts of ocular connective tissue cells on monocytes, a major cellular component of the circulating immune system.

METHODS

Primary human Tenon's capsule fibroblasts derived from five unrelated patients were activated into myofibroblasts in 3D collagen matrices under isometric tension, with and without exposure to an inflammatory cytokine-enhanced milieu, and co-cultured with an immortalized human monocyte cell line (THP-1 cells). Quantitative PCR analyses were performed on 8 candidate genes to assess the impacts of inflammatory cytokines on the myofibroblasts and the monocytes in mono-cultures and compared to cells in co-culture to clearly distinguish any co-culture-induced impacts on gene expression.

RESULTS

Our data indicate that both Tenon's capsule myofibroblasts in 3D mono-culture and THP-1 monocytes in suspension mono-culture were responsive to inflammatory cytokine stimuli. Co-culture with Tenon's capsule myofibroblasts significantly modulated the gene expression responses of THP-1 monocytes to inflammatory cytokine stimulation, indicative of an immunomodulatory "feedback" system between these cell types.

CONCLUSION

Our findings provide proof of principle for the use of simple 3D co-culture systems as a means to enhance our understanding of ocular stromal cell interactions with cells of the innate immune system and to provide more informative in vitro models of inflammation-associated ophthalmic pathologies.

A Novel System for Measuring Pterygium's Progress Using Deep Learning

Pterygium is a common ocular surface disease. When pterygium significantly invades the cornea, it limits eye movement and impairs vision, which requires surgery to remove. It is medically recognized that when the width of the pterygium that invades the cornea is >3 mm, the patient can be treated with surgical resection. Owing to this, this study proposes a system for diagnosing and measuring the pathological progress of pterygium using deep learning methods, which aims to assist doctors in designing pterygium surgical treatment strategies. The proposed system only needs to input the anterior segment images of patients to automatically and efficiently measure the width of the pterygium that invades the cornea, and the patient's pterygium symptom status can be obtained. The system consists of three modules, including cornea segmentation module, pterygium segmentation module, and measurement module. Both segmentation modules use convolutional neural networks. In the pterygium segmentation module, to adapt the diversity of the pterygium's shape and size, an improved U-Net++ model by adding an Attention gate before each up-sampling layer is proposed. The Attention gates extract information related to the target, so that the model can pay more attention to the shape and size of the pterygium. The measurement module realizes the measurement of the width and area of the pterygium that invades the cornea and the classification of pterygium symptom status. In this study, the effectiveness of the proposed system is verified using datasets collected from the ocular surface diseases center at the Affiliated Eye Hospital of Nanjing Medical University. The results obtained show that the Dice coefficient of the cornea segmentation module and the pterygium segmentation module are 0.9620 and 0.9020, respectively. The Kappa consistency coefficient between the final measurement results of the system and the doctor's visual inspection results is 0.918, which proves that the system has practical application significance.

SPARC knockdown attenuated TGF-β1-induced fibrotic effects through Smad2/3 pathways in human pterygium fibroblasts

PURPOSE

Secreted protein acidic and rich in cysteine (SPARC), a matricellular glycoprotein, has been found to regulate processes involved in fibrotic diseases. The aim of this study was to investigate the anti-fibrotic effects of SPARC in primary human pterygium fibroblasts (HPFs) and elucidate the underlying mechanisms.

METHODS

The expression of SPARC in HPFs was knocked down by RNA interference-based approach. Subsequently, we examined the expression of profibrotic markers induced by transforming growth factor-β1 (TGF-β1), including type 1 collagen (COL1), α-smooth muscle actin (α-SMA), and fibronectin (FN). The changes in signaling pathways and matrix metalloproteinases (MMPs) were also detected by western blotting. The cellular migration ability, proliferation ability, apoptosis, and contractile phenotype were detected using the wound healing assay, Cell Counting Kit-8 assay, flow cytometry, and collagen gel contraction assay, respectively. The interaction between SPARC and TGF-β RII was detected by Co-IP RESULTS: Silencing of SPARC inhibited the basal and TGF-β1-induced expression of COL1, α-SMA, and FN in HPFs, and suppressed the expression of p-Smad2, p-Smad3, Smad4 and MMP2, MMP9. The downregulation of SPARC also attenuated the cell migration and contractile phenotype of HPFs. SPARC could bind to TGF-βRII under TGF-β1 treatment. However, knockdown of SPARC did not affect the proliferation and apoptosis of HPFs.

CONCLUSION

SPARC knockdown attenuated the fibrotic effect induced by TGF-β1 at least in part by inactivating the Smad2/3 pathways in HPFs. Therefore, SPARC may be a promising therapeutic target for the treatment of pterygium.

RhoA/ROCK Signaling Regulates TGF-β1-Induced Fibrotic Effects in Human Pterygium Fibroblasts through MRTF-A

PURPOSE

The overexpression of transforming growth factor-beta1 (TGF-β1) after surgical excision often leads to excessive fibrosis, indicating the recurrence of pterygium. The aims of the present in vitro study were to investigate the role of RhoA/ROCK signaling in regulating fibrotic effects of primary human pterygium fibroblasts (HPFs), as well as to explore the possible mechanisms of these effects.

METHODS

Pterygium samples were obtained from surgery, and profibrotic activation was induced by TGF-β1. Cell proliferation was detected by CCK-8 assay; cell migration was detected by wound healing assay; quantitative real-time PCR and Western blot were used to detect the effects of TGF-β1 and the role of RhoA/ROCK signaling in the synthesis of alpha-smooth muscle actin (a-SMA), type I and III collagen (COL1 and COL3), and matrix metalloproteinase-9 (MMP9) in HPFs. The changes of signaling pathways were detected by Western blot; and pharmaceutical inhibition of RhoA/ROCK signaling and its downstream MRFT-A/SRF transcription pathway were used to assess their possible mechanism in HPFs fibrosis.

RESULTS

ROCK inhibitor Y-27632 decreased TGF-β1-induced cell proliferation and migration, reduced the TGF-β1-induced expression of profibrotic markers in HPFs, and suppressed TGF-β1-induced nuclear accumulation of Myocardin-related transcription factor A (MRTF-A) as well as accompanied elevation of F/G-actin ratio in HPFs. MRTF-A/Serum response factor (SRF) inhibitor CCG-100602 attenuated the TGF-β1-induced α-SMA expression and reduced myofibroblast activation in HPFs.

CONCLUSIONS

RhoA/ROCK signaling played a pivotal role in TGF-β1-induced fibrosis and myofibroblast activation in HPFs at least in part by inactivating the downstream MRTF-A/SRF transcriptional pathway.

Evaluation of Primary Pterygia on Basis of the Loss of Vertical Length of Plica Semilunaris

Purpose

To propose a new grading system for primary pterygia based on the morphological loss of vertical length of plica semilunaris (LPS).

Methods

We included 50 eyes from 41 patients with primary pterygium. LPS was defined and quantified as the ratio of the length of loss of the normal vertical morphology at plica semilunaris to the vertical corneal diameter using anterior-segment photographs. Grades of tear metalloproteinase 9 (MMP-9) expression by point-of-care immunoassay, which is a well-known biomarker for inflammation, was correlated with the extent of LPS (%) of pterygia. Then, LPS was paralleled with the pre-established grading systems on the basis of tissue translucency (i.e., T grade) and vascularity (i.e., V grade) of the pterygium body.

Results

MMP-9 grades was 2.39 ± 1.12 in the group with LPS ≥50% and was 1.56 ± 1.12 in the group with LPS <50% (P = 0.016). In a linear regression, the extent of LPS was positively correlated with MMP-9 grades (r = 0.315, P = 0.026). MMP-9 expression did not differ between T grades or V grades. The extents of LPS were well correlated positively with both T grades (r = 0.495 and P < 0.001) and V grades (r = 0.344 and P = 0.015).

Conclusions

We devised a new grading system using LPS on the basis of morphological loss of the normal vertical plica semilunaris in primary pterygia. The extent of LPS correlated well with T grades and V grades and also reflected the expression of MMP-9 in tears.

Translational Relevance

The new clinical LPS grading system reflects severity and MMP-9 expression in tears in primary pterygia.

Inhibitory Effect of Valsartan on Pterygium Fibroblasts

PURPOSE

Angiotensin receptor blockers (ARBs) were shown to have antifibrotic properties in ocular and systemic diseases. In this study, our aim was to investigate the effect of an angiotensin receptor blocker, valsartan, on pterygium fibroblasts and compare this effect with that of mitomycin C (MMC).

METHODS

Pterygium tissue samples were obtained from 3 patients during surgical excision. Primary cultured pterygium fibroblasts and L929 cell cultures were treated with different concentrations of MMC and valsartan.

RESULTS

The cell viability decreased with increasing concentrations of valsartan at 48 hours for both cell types. MMC inhibited the proliferation of both cell types at 48 hours. Both agents significantly decreased the cell migration of the 2 cell types, although it was more prominent in the MMC-treated group.

CONCLUSIONS

Valsartan inhibited the proliferation and migration of pterygium fibroblasts. The known favorable safety profile of these drugs and the results of this study showing inhibitory effect on pterygium fibroblasts make valsartan a potential therapeutic agent for pterygium treatment.

Bibliometric analysis and mapping knowledge domain of pterygium: 2000-2019

AIM

To track the knowledge structure, topics in focus, and trends in emerging research in pterygium in the past 20y.

METHODS

Base on the Web of Science Core Collection (WoSCC), studies related to pterygium in the past 20y from 2000-2019 have been included. With the help of VOSviewer software, a knowledge map was constructed and the distribution of countries, institutions, journals, and authors in the field of pterygium noted. Meanwhile, using co-citation analysis of references and co-occurrence analysis of keywords, we identified basis and hotspots, thereby obtaining an overview of this field.

RESULTS

The search retrieved 1516 publications from WoSCC on pterygium published between 2000 and 2019. In the past two decades, the annual number of publications is on the rise and fluctuated a little. Most productive institutions are from Singapore but the most prolific and active country is the United States. Journal Cornea published the most articles and Coroneo MT contributed the most publications on pterygium. From co-occurrence analysis, the keywords formed 3 clusters: 1) surgical therapeutic techniques and adjuvant of pterygium, 2) occurrence process and pathogenesis of pterygium, and 3) epidemiology, and etiology of pterygium formation. These three clusters were consistent with the clustering in co-citation analysis, in which Cluster 1 contained the most references (74 publications, 47.74%), Cluster 2 contained 53 publications, accounting for 34.19%, and Cluster 3 focused on epidemiology with 18.06% of total 155 co-citation publications.

CONCLUSION

This study demonstrates that the research of pterygium is gradually attracting the attention of scholars and researchers. The interaction between authors, institutions, and countries is lack of. Even though, the research hotspot, distribution, and research status in pterygium in this study could provide valuable information for scholars and researchers.

Recurrent pterygium: A review

Purpose:

To summarize the recent evidence regarding different aspects of pterygium recurrence.

Methods:

Human-based studies from PubMed, Scopus, and Google Scholar were identified using the following keywords: conjunctival disease, pterygium, recurrent pterygium, pterygium recurrence, pterygium management/surgery, conjunctival autograft (CAU), amniotic membrane graft/transplant, and adjuvant therapy (January 2009 to February 2021). We reviewed risk factors associated with the recurrence of pterygium, timing of recurrence, medical treatments to prevent from recurrence, and nonsurgical and surgical alternatives for management of recurrence.

Results:

Dry eye disease, black race, and young age are considered definite risk factors for recurrence. However, fleshy appearance of the pterygium and preoperative size remain controversial. Surgical techniques such as excessive suturing, insufficient conjunctival graft size, thick conjunctival graft with remained Tenon tissue, and postoperative graft retraction are considered possible risk factors for recurrence. Using fibrin glue instead of sutures can further reduce recurrence rates. Although recurrence could occur even after many years, most recurrences happen in the first 3–6 months after surgery. Multiple kinds of adjuvant medications are used before, during, or after the operation including mitomycin C (MMC), 5-fluorouracil (5-FU), corticosteroids, and anti-vascular endothelial growth factors (anti-VEGFs). Multiple weekly subconjunctival 5-FU injections are shown to be safe and effective in halting the progression of recurrent pterygium. Although topical bevacizumab is found to inhibit the growth of impending recurrent pterygium, the effect is mostly temporary. CAU is superior to amniotic membrane transplantation in the treatment for recurrent pterygia.

Conclusions:

There is yet to be a panacea in treating recurrent pterygium. Currently, there is not a globally accepted recommendation for treating recurrent pterygium with anti-VEGFs or 5-FU as a nonsurgical treatment. We strongly recommend using MMC as an adjunct to surgery in recurrent cases, with consideration of its specific complications. CAU is the most effective surgical treatment for recurrent pterygium, and other new surgical therapies need further investigation.

Role of Surgeon Experience in Pterygium Surgical Outcomes: A Comparative Study Between Ophthalmology Resident and Consultant

Purpose

Although surgical technique and patient variables are responsible for the recurrence of pterygium, the surgeon's experience has been sparsely studied. This retrospective study was designed to compare the surgical time, complications, and rates of recurrence after primary pterygium excision between consultant ophthalmologists and trainee residents.

Material and methods

In this retrospective study, we collected the data of 176 primary pterygium eyes, who were operated on with excision and sutureless/glueless conjunctival autograft either by the consultant (group A) or by the trainee (group B). The demographic profile, surgical time, complications, and recurrences between both groups were analyzed.

Results

Both the groups were comparable with regards to age, gender, religion, side of the eye, size of the pterygium, and duration of follow-up. The mean operative time was longer in group B (26.5+/-3.8 minutes) than group A (14.2+/-1.6 minutes). Though a relatively higher percentage of complications was observed in group B (12% vs. 9%), the difference was statistically not significant (Mann-Whitney U test, p-value 0.271). There was no statically significant difference in recurrence rate (6.8% vs 9.4%) between the groups.

Conclusion

With regards to the role of surgeon experience in primary pterygium excision using the sutureless and glueless conjunctival autografting technique, the residents did not have any statistically significant differences in their postoperative complications and recurrence rates. However, the surgical time was significantly higher in the resident group owing to the learning curve.

Identification of Functional Genes in Pterygium Based on Bioinformatics Analysis

Purpose

The competing endogenous RNA (ceRNA) network regulatory has been investigated in the occurrence and development of many diseases. This research aimed at identifying the key RNAs of ceRNA network in pterygium and exploring the underlying molecular mechanism.

Methods

Differentially expressed long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs were obtained from the Gene Expression Omnibus (GEO) database and analyzed with the R programming language. LncRNA and miRNA expressions were extracted and pooled by the GEO database and compared with those in published literature. The lncRNA-miRNA-mRNA network was constructed of selected lncRNAs, miRNAs, and mRNAs. Metascape was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses on mRNAs of the ceRNA network and to perform Protein-Protein Interaction (PPI) Network analysis on the String website to find candidate hub genes. The Comparative Toxicogenomic Database (CTD) was used to find hub genes closely related to pterygium. The differential expressions of hub genes were verified using the reverse transcription-real-time fluorescent quantitative PCR (RT-qPCR).

Result

There were 8 lncRNAs, 12 miRNAs, and 94 mRNAs filtered to construct the primary ceRNA network. A key lncRNA LIN00472 ranking the top 1 node degree was selected to reconstruct the LIN00472 network. The GO and KEGG pathway enrichment showed the mRNAs in ceRNA networks mainly involved in homophilic cell adhesion via plasma membrane adhesion molecules, developmental growth, regulation of neuron projection development, cell maturation, synapse assembly, central nervous system neuron differentiation, and PID FOXM1 PATHWAY. According to the Protein-Protein Interaction Network (PPI) analysis on mRNAs in LINC00472 network, 10 candidate hub genes were identified according to node degree ranking. Using the CTD database, we identified 8 hub genes closely related to pterygium; RT-qPCR verified 6 of them were highly expressed in pterygium.

Conclusion

Our research found LINC00472 might regulate 8 hub miRNAs (miR-29b-3p, miR-183-5p, miR-138-5p, miR-211-5p, miR-221-3p, miR-218-5p, miR-642a-5p, miR-5000-3p) and 6 hub genes (CDH2, MYC, CCNB1, RELN, ERBB4, RB1) in the ceRNA network through mainly PID FOXM1 PATHWAY and play an important role in the development of pterygium.

Relative gene expression analysis of human pterygium tissues and UV radiation-evoked gene expression patterns in corneal and conjunctival cells

A sight threatening, pterygium is a common ocular surface disorders identified by fibrovascular growth of the cornea and induced by variety of stress factors, like ultraviolet (UV) exposure. However, the genes involved in the etiopathogenesis of this disease is not well studied. Herein, we identified the gene expression pattern of pterygium and examined the expression of pterygium-related genes in UV-B-induced human primary cultured corneal epithelial cells (HCEpCs), telomerase immortalized human corneal epithelial (hTCEpi), primary conjunctival fibroblast (HConFs) and primary pterygium fibroblast cells (HPFCs). A careful analysis revealed that the expression of 10 genes was significantly modulated (by > 10-fold). Keratin 24 (KRT24) and matrix metalloproteinase 9 (MMP-9) were dramatically upregulated by 49.446- and 24.214-fold, respectively. Intriguingly, UV-B exposure (50 J/m²) induced the upregulation of the expressions of MMP-9 in corneal epithelial cells such as HCEpCs and hTCEpi. Furthermore, UV-B exposure (100 and/or 200 J/m²) induced the upregulation of the expressions of MMP-9 in fibroblast such as HConFs and HPFCs. The exposure of HCEpCs to 100 and 200 J/m² UV-B induced significant expressions of KRT24 mRNA. Nevertheless, no expression of KRT24 mRNA was detected in HConFs and HPFCs. The findings provide evidence that the progression of pterygium may involve the modulation of extracellular matrix-related genes and vasculature development and the up-regulation of KRT24 and MMP-9 by UV stress. UV radiation may promote the modulation of these pterygium-related genes and induce the initiation and progression of human pterygium.

Targeted delivery of mitomycin C-loaded and LDL-conjugated mesoporous silica nanoparticles for inhibiting the proliferation of pterygium subconjunctival fibroblasts

Pterygium is a degenerative disease that characterized by excessive fibrovascular proliferation. To reduce the recurrence rate, surgery is the main strategy, in combination with adjacent procedures or adjunctive therapy. One of the most common adjunctive agents, mitomycin C (MMC), is known as an alkylating agent that inhibits fibroblast proliferation but is limitedly applied in pterygium due to various complications. A previous study demonstrated that activated pterygium subconjunctival fibroblasts overexpressed low-density lipoprotein (LDL) receptors. In this study, we designed and synthesized MMC-loaded mesoporous silica nanoparticles conjugated with LDL (MMC@MSNs-LDL) to deliver MMC into activated pterygium fibroblasts in a targeted manner. The MMC loading efficiency was approximately 6%. The cell viability test (CCK-8 assay) revealed no cytotoxicity for the empty carrier MSNs at a concentration of ≤1 mg/ml after administration for 48 h in subconjunctival fibroblasts. Primary pterygium and normal human subconjunctival fibroblasts with or without stimulation by vascular endothelial growth factor (VEGF) were treated as follows: 1) 10 μg/ml MMC@MSNs-LDL for 24 h (MMC concentration: 0.6 μg/ml); 2) 0.2 mg/ml MMC for 5 min then cultured for 24 h after MMC removal; and 3) normal culture without any drug treatment. At 24 h, the anti-proliferative effect of MMC@MSNs-LDL in activated pterygium fibroblasts was similar to that of MMC (cell viability: 46.2 ± 5.5% vs 40.5 ± 1.1%, respectively, P = 0.349). Furthermore, the cytotoxicity of MMC@MSNs-LDL to normal fibroblasts with or without VEGF stimulation was significantly lower than that of traditional MMC (cell viability: 75.6 ± 4.4% vs 36.0 ± 1.5%, respectively, P < 0.001; 84.7 ± 5.5% vs 35.7 ± 1.3%, P < 0.001). The binding of fluorescently labeled MMC@MSNs-LDL in fibroblasts was assessed using confocal fluorescence microscopy. The uptake of targeted nanoparticles in fibroblasts was time dependent and saturated at 6 h. VEGF-activated pterygium fibroblasts showed more uptake of MMC@MSNs-LDL than normal fibroblasts with or without VEGF activation (both P < 0.001). Our data strongly suggest that MMC@MSNs-LDL had an effective antiproliferative role in activated pterygium fibroblasts, with reduced toxicity to normal fibroblasts compared to traditional application of MMC. LDL-mediated drug delivery might have great potential in the management of pterygium recurrence.

DNA methylation of miR-200 clusters promotes epithelial to mesenchymal transition in human conjunctival epithelial cells

Epithelial to mesenchymal transition (EMT) contributes to fibrosis associated pathologies including scarring of different ocular tissues. Recently targeting EMT is seen as an appropriate therapeutic approach for different fibrosis related eye diseases such as macular degeneration or glaucoma surgery related fibrosis. Nevertheless, for ocular surface diseases, target genes specific for particular cell type or condition are still undefined. This study aimed to expose the complex regulatory mechanisms that trigger EMT in human conjunctival epithelial (HCjE) cells. EMT was induced by prolonged treatment with two TGF-β isoforms, TGF-β1 and TGF-β2, and their combination. TGF-β1 showed the strongest potential for initiating EMT in HCjE cells, reflected on morphological changes, cell migration and the levels of mRNA expression of different epithelial (CDH1, OCLN, DSP) and mesenchymal (CDH2, FN1, VIM, SNAI1, ZEB2, TWIST1) marker genes. Co-treatment with the DNA demethylating agent 5-Azacytidine (5-AzaC) was capable of stopping the transition of HCjE cells towards a mesenchymal phenotype, based on morphological features, reduced cell mobility and mRNA and protein expression levels of epithelial and mesenchymal marker genes. An EMT qRT-PCR-based array revealed that EMT induced considerable alterations in gene expression, with downregulation of the majority of epithelial marker genes and upregulation of genes specific for the mesenchymal state. The major effect of 5-AzaC treatment was observed as a suppression of mesenchymal marker genes, suggesting the involvement of upstream negative regulator(s) whose promoter demethylation and subsequent expression will in turn promote EMT switch off. The expression level of miRNAs potentially important for EMT induction was determined using qRT-PCR-based array which pointed at members of miR-200 family as main regulators of EMT process in HCjE cells. 5-AzaC treatment induced increased expression of miR-200a, -200b, -200c and miR-141 towards the control level, indicating important role of DNA methylation in their regulation. The DNA methylation status of both miR-200 family clusters, analyzed with high-resolution melting (HRM) and bisulfite sequencing (Bis-Seq), revealed that TGF-β1-induced EMT was accompanied by increase in promoter CpG methylation of both miR-200 loci, which was reverted after 5-AzaC treatment. In conclusion, our results indicate that DNA demethylation of promoters of miR-200 loci is critically important for stopping and reverting the EMT in human conjunctival epithelial cells, suggesting the potential for the development of novel epigenetic-based therapeutic strategies for treating conjunctival conditions associated with EMT.

Femtosecond Laser-assisted Preparation of Conjunctival Autograft for Pterygium Surgery

Femtosecond laser-assisted conjunctival autografts (CAG) preparation was recently proposed. This study reports the outcomes of the first clinical trial on the use of laser to prepare CAG in pterygium surgery, and to compare the outcomes with those of manual technique. Forty eyes undergoing primary pterygium excision with laser-assisted CAG transplantation were prospectively included (L group). Two historical matched cohorts whose CAGs were prepared manually were compared (n = 78 eyes by the same experienced surgeon, M group; n = 78 eyes by trainees; TM group). We found the laser-created CAGs had only 11 μm deviation from the targeted thickness. The best-corrected visual acuity improved, and the astigmatism significantly decreased after surgery, with comparable efficacy across 3 groups. The 1-year recurrence rate was 2.5%, 3.8% and 7.7% in the L, M and TM groups, respectively (P = 0.12). There was no significant difference between the L and M groups in the complication rate (5.0% and 1.3%, respectively), surgical time (19.4 ± 5.1 and 19.1 ± 6.2 minutes, respectively), and postoperative discomfort scores (0.1 ± 0.3 and 0.2 ± 0.3, respectively), but these outcomes were significantly less favorable in the TM group. The results of this first comparative clinical trial suggest that femtosecond laser-assisted CAG preparation can be considered as an alternative technique for CAGs preparation.

Evaluation of Neutrophil-Lymphocyte Ratios, Mean Platelet Volumes, and Platelet-Lymphocyte Ratios in Pterygium

Objectives:

To assess the neutrophil-to-lymphocyte ratio (NLR), mean platelet volumes (MPV), platelet–lymphocyte ratios (PLR) and other complete blood count parameters (CBC) as indicators of inflammation in patients with pterygium.

Methods:

This study was carried out retrospectively in 111 consecutive pterygium patients and 106 control subjects. Laboratory and clinical parameters were obtained from the patient data management system. NLR and PLR were calculated by dividing neutrophil and platelet count by lymphocyte count.

Results:

A significant difference was found in NLR and lymphocyte values between the pterygium and control groups (p<0.05). However, there was no significant difference found in MPV, PLR and other parameters between groups (p>0.05).

Conclusion:

NLR may have an association with pterygium, which should be investigated at larger subgroups in further studies.

Targeting platelet-derived growth factor receptor β inhibits the proliferation and motility of human pterygial fibroblasts

Background: Pterygium, a common eye disease with high postoperative recurrence, lacks effective therapeutic strategies. Therefore, it's urgent to identify specific targets to develop rationally targeted molecular drugs for the pterygial therapy. Methods: The cell proliferation and motility were studied in both the primary human pterygial fibroblasts (hPFs) and an ex vivo pterygium model. hPFs transfected with the pCMV3-PDGFRB plasmid, PDGFRB siRNA and CRISPR/Cas9 system were used to determine the role of PDGFR-β in pterygial fibroblasts functions. Western blotting, immunohistochemistry and immunofluorescence were performed to evaluate the expression of the key proteins. Results: PDGFR-β expression in the pterygial stroma and primary hPFs was significantly higher than that in the conjunctiva and human conjunctival fibroblasts. PDGF-BB promoted the proliferation, migration and invasion of hPFs, which can be significantly suppressed by sunitinib via inhibition of the PDGFR-β/extracellular signal-regulated kinase (ERK) pathway. In the ex vivo model, the knockout of PDGFRB and sunitinib treatment blocked the proliferation and motility of fibroblasts in the pterygial stroma via the suppression of PDGFR-β/ERK pathway. Conclusion: This study demonstrates that PDGFR-β may be a potential therapeutic target for pterygium, and inhibition of PDGFR-β by sunitinib is a promising and effective approach for pterygium treatment.

Management of primary pterygium with intra-lesional injection of 5 flurouracil and bevacizumab (Avastin)

BACKGROUND

To assess the efficacy of combined 5FU and Avastin injections in the treatment of primary pterygium METHODS: Sixteen eyes with primary pterygium received intralesional 5 fluorouracil and Avastin (2.5-5 mg) injections every 2 weeks for a maximum of five injections. Fourteen eyes of 14 patients received five injections, one eye received three injections and one eye received two injections. All eyes were followed at monthly intervals for 3 months after last injection. Tissue was obtained by surgical excision of primary pterygium from four eyes who received injections and three eyes with primary pterygium who did not receive injections (control) and subjected to immunohistological examination for beta fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), von-Willebrand factor (vWF), lymphatic vessel endothelial hyaluronan receptor (LYVE-1) and collagen-I.

RESULTS

Pterygium progression was arrested in all patients. Sixty-two percent of patients had improvement of redness while 89% had reduced thickness of the lesion. VEGF, bFGF, EGF, vWF, LYVE-1 and collagen-I were all reduced in the injected samples.

CONCLUSIONS

The injection of 5 fluorouracil and Avastin act synergistically to arrest progression and induce atrophy in primary pterygium. This is related to the effect of agents on fibroblasts, collagen, and vascular tissues. Such medical intervention is a safe and viable option in the management of primary pterygium though excision of residual tissue is still required in some cases. Longer follow up is needed to ascertain whether this will reduce the recurrence rate following excision.

Assessment of miR-182, miR-183, miR-184, and miR-221 Expressions in Primary Pterygium and Comparison With the Normal Conjunctiva

OBJECTIVES

The aim of this study was to investigate the expression levels of miR-126-3p, miR-182-5p, miR-183-5p, miR-184, miR-221-3p, and miR-205-5p in primary pterygium tissue and compare these levels with those in healthy conjunctiva tissue.

METHODS

Twenty-four patients who were diagnosed with grade 3 primary pterygium and scheduled for surgery between January 2014 and January 2016 and had no systemic disease or other ocular pathology were included in the study. The control group comprised nasal interpalpebral conjunctival tissue specimens from 24 age- and sex-matched patients with no history of systemic disease or ocular pathology other than cataract. Expression levels of miR-126-3p, miR-182-5p, miR-183-5p, miR-184, miR-221-3p, and miR-205-5p were determined and compared between the pterygium and conjunctiva specimens.

RESULTS

Expression levels of miR-182-5p, miR-183-5p, and miR-184 were significantly higher in pterygium tissue compared with normal conjunctival specimens (P<0.0001, P=0.01, and P=0.01, respectively), whereas expression of miR-221-3p was significantly lower (P=0.02). Expression levels of miR-126-3p and miR-205-5p did not differ significantly between the 2 groups (P>0.05).

CONCLUSIONS

Expression levels of miR-182-5p, miR-183-5p, and miR-184 are increased, whereas expression of miR-221-3p is decreased in primary pterygium tissue, and these miRNAs may play a role in the pathogenesis of pterygium.

Induction of Apoptosis in Pterygium Cells by Antagonists of Growth Hormone-Releasing Hormone Receptors

Purpose

The aim of the study was to investigate the signaling of growth hormone-releasing hormone receptor (GHRH-R) in the pathogenesis of pterygium and determine the apoptotic effect of GHRH-R antagonist on pterygium epithelial cells (PECs).

Methods

Fourteen samples of primary pterygium of grade T3 with size of corneal invasion ≥ 4 mm were obtained for investigation by histology, immunofluorescence, electron microscopy, explant culture, and flow cytometry.

Results

We found that PECs were localized in the basal layer of the epithelium in advancing regions of the head of pterygium. These cells harbored clusters of rough endoplasmic reticulum, ribosomes, and mitochondria, which were consistent with their aggressive proliferation. Immunofluorescence studies and Western blots showed that GHRH-R and the downstream growth hormone receptor (GH-R) were intensively expressed in PECs. Their respective ligands, GHRH and GH, were also elevated in the pterygium tissues as compared to conjunctival cells. Explanted PECs were strongly immunoreactive to GHRH-R and exhibited differentiation and proliferation that led to lump formation. Treatment with GHRH-R antagonist MIA-602 induced apoptosis of PECs in a dose-dependent manner, which was accompanied by a downregulation of ERK1 and upregulation of Caspase 3 expression.

Conclusions

Our results revealed that GHRH-R signaling is involved in survival and proliferation of PECs and suggest a potential therapeutic approach for GHRH-R antagonist in the treatment of pterygium.

Signaling roadmap to epithelial-mesenchymal transition in pterygium, TWIST1 centralized

Pterygium as a complex disease shares common features with other malignant cells in its onset recurrence and especially epithelial-mesenchymal transition (EMT) transition. Although using different approaches including conjunctival autografts, amniotic membrane, radiotherapy, mitomycin C (MMC) has shown promising insights in the inhibition of pterygium recurrence, it needs to be investigated in more details in molecular pathways to present adjuvant target therapy. In this study, we aimed to evaluate the expression of and then illustrate the role of signaling pathways on EMT in pterygium. Using real-time polymerase chain reaction, the twist-related protein 1 (TWIST1) expression was compared in primary pterygium and normal conjunctiva. This study assessed the mRNA expression, as well as the association between the clinicopathological indices and the gene expression level. The expression level of TWIST1 was overexpressed in 36% of our cohort ( n = 76). There was a significant positive correlation between recurrence with grade T, grade V and a significant negative correlation with growth activity. Our vast literature review on different signaling pathways in pterygium showed that EMT has centralization role in recurrence of this disease. Our data confirmed that EMT is important in the recurrence of pterygium samples and different signaling pathways end up activating the EMT markers. It is suggested to evaluate the environmental factors and their correlation with molecular markers to select favorable treatment for this kind of diseases.

Association between Blepharoptosis and Pterygium in Korea: A Population-Based Study during 2010-2012

PURPOSE

To investigate possible correlations between blepharoptosis and pterygium in a nationally representative sample of the Korean population.

METHODS

This population-based, cross-sectional study was comprised of 3,685 males and 4,792 females (≥ 19 years of age) participating in the fifth annual Korea National Health and Nutrition Examination Survey (KNHANES) from 2010 to 2012. The enrolled subjects underwent interviews, clinical examinations, and laboratory tests. Statistical tests were used to compare the prevalence of blepharoptosis, according to pterygium subtypes or pterygium existence. Multiple logistic regression analyses were also used to find the associations of blepharoptosis with pterygium.

RESULTS

Pterygium was present in 10.3% of males and 9.8% of females. The odds ratios (ORs) of pterygium in Korean males significantly decreased as the severity of blepharoptosis increased (p for trend = 0.0252). Using three models in multivariate analyses, males with blepharoptosis had an OR (95% confidence interval, (CI)) of 0.643 (0.435 ~ 0.951) for pterygium compared with males with no blepharoptosis, after adjusting for age, body mass index, smoking status, alcohol consumption, physical activity, serum vitamin D levels, diabetes mellitus, metabolic syndrome, high blood pressure, and stress intolerance. There was no significant association between blepharoptosis and females.

CONCLUSIONS

The association between blepharoptosis and pterygium in the Korean population showed a gender difference. Epidemiologic evidence only showed a negative correlation between blepharoptosis and pterygium in Korean males. Further studies are needed, therefore, to examine the sex difference in the pathogenesis of pterygium.

Bromfenac Inhibits TGF-β1-Induced Fibrotic Effects in Human Pterygium and Conjunctival Fibroblasts

Purpose

Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown antifibrotic effects on several diseases. The aims of the present in vitro study were to investigate the antifibrotic effects of bromfenac (a kind of NSAID) on primary human pterygium fibroblasts (HPFs) and primary human conjunctival fibroblasts (HConFs), as well as to explore the possible mechanisms of these effects.

Methods

The cells used in this study were primary HPFs and HConFs, and profibrotic activation was induced by transforming growth factor-beta1 (TGF-β1). Western blot, quantitative real-time PCR, and immunofluorescence (IF) assays were used to detect the effects of TGF-β1 and bromfenac on the synthesis of fibronectin (FN), type III collagen (COL3), and alpha-smooth muscle actin (α-SMA) in HPFs and HConFs; the changes of signaling pathways were detected by Western blot; cell migration ability was detected by wound healing assay; cell proliferation ability was detected by CCK-8 assay; and pharmaceutical inhibitions of the downstream signaling pathways of TGF-β1 were used to assess their possible associations with the effects of bromfenac.

Results

Bromfenac suppressed the TGF-β1-induced protein expression of FN (0.59 ± 0.07 folds, P = 0.008), COL3 (0.48 ± 0.08 folds, P = 0.001), and α-SMA (0.61 ± 0.03 folds, P = 0.008) in HPFs. Bromfenac also attenuated TGF-β1-induced cell migration (0.30 ± 0.07 folds, P < 0.001), cell proliferation (0.64 ± 0.03 folds, P = 0.002) and the expression levels of p-AKT (0.66 ± 0.08 folds, P = 0.032), p-ERK1/2 (0.69 ± 0.11 folds, P = 0.003), and p-GSK-3β-S9 (0.65 ± 0.10 folds, P = 0.002) in HPFs. PI3K/AKT inhibitor (wortmannin) and MEK/ERK inhibitor (U0126) reduced the TGF-β1-induced synthesis of FN, COL3, and α-SMA in HPFs. All the results were similar in HConFs.

Conclusions

Bromfenac protects against TGF-β1-induced synthesis of FN, α-SMA, and COL3 in HPFs and HConFs at least in part by inactivating the AKT and ERK pathways.

Outcomes of Vertical Split Conjunctival Autograft Using Fibrin Glue in Treatment of Primary Double-Headed Pterygia

Purpose

To evaluate the efficiency of pterygium excision with the vertical split conjunctival technique using fibrin glue in treatment of primary double-headed pterygia.

Patients and Methods

15 eyes of 15 patients with primary double-headed pterygia that underwent vertical split conjunctival autograft pterygium surgery were retrospectively reviewed. Recurrence was defined as fibrovascular proliferation over the limbus onto the cornea.

Results

The patients' mean age was 36.92 ± 10.8 years. At 12-month follow-up, recurrence was not seen in any cases. Regarding postoperative cosmetic grading, grade 1 (the appearance of the operated site is not different from the normal appearance) was found in 12 eyes (80%) and grade 2 (some fine episcleral vessels in the excised area extending up to but not beyond the limbus and without fibrous tissue) was found in 3 eyes (20%). None of the cases showed conjunctival scarring or fibrosis at the conjunctival donor area. Preoperative Sim K astigmatism at the central 3 mm and BCVA were 3.05 ± 1.5 diopters (D) and 0.64 ± 0.26 logMAR, which improved significantly to 1.15 ± 0.84 D and 0.26 ± 0.18 logMAR at 12-month follow-up postoperatively, respectively.

Conclusion

Vertical split conjunctival autograft using fibrin glue is an effective technique with good cosmetic results and low to no recurrence for primary double-headed pterygia treatment. This trial is registered with NCT03507283.

Healing of autologous conjunctival grafts in pterygium surgery

PURPOSE

To temporally study the healing of conjunctival autografts in consecutive patients following pterygium surgery.

METHODS

A case-cohort observational study. Thirty-two eyes of 28 patients who underwent pterygium surgery were included. All eyes had pterygium excision with conjunctival autografts. Twenty-seven eyes of 24 patients underwent excision of primary pterygium while five eyes of four patients had surgery for recurrent pterygium. All grafts were attached using fibrin glue. Mitomycin-C 0.04% was used intraoperatively in 25 eyes. All eyes were followed up at 1, 2, 4, 8, 12 weeks and 6 months postoperatively. Photographs were taken at each visit to monitor graft vessels, re-perfusion and healing. Main outcome measures were graft loss; re-perfusion of grafts and appearance and resolution of oedema, transudation and haemorrhage; approximation of graft edges to host bed and changes at donor site.

RESULTS

No graft tissue was lost. In all eyes, healing of autografts started with graft swelling due to oedema and transudation followed by re-perfusion injury, which manifested as swelling, variable vessels calibre, patchy or diffuse haemorrhage occurring within first week and resolving by fourth postoperative week. Graft vessels anastomose with vessels in surrounding conjunctiva and underlying episclera to re-establish blood circulation. Retraction of graft edges from surrounding conjunctiva was uncommon with rapid epithelialization of exposed (epi)sclera.

CONCLUSION

Conjunctival autografts in pterygium surgery follow a consistent healing pattern dominated by re-perfusion injury in early postoperative days. This produces dramatic changes in the autograft for which patients should be counselled before surgery. Conjunctival autografts are not at risk of falling off, losing epithelial cover or undergoing necrosis.

How to minimize pterygium recurrence rates: clinical perspectives

The main treatment for pterygium is surgical removal. However, pterygium surgery is concerned with high rates of postoperative recurrence. Predicting factors of recurrence are not fully understood, yet, but they probably depend on a multitude of patient-related, clinical, and/or surgical factors. Several adjuvant treatments have been proposed to reduce postoperative pterygium recurrence, including different antimetabolites, antiangiogenetic factors, and radiation therapy. The purpose of this review is to collect the current evidence regarding application and limits of different therapeutic approaches for preventing postoperative recurrence of pterygium, giving insights and perspectives for better management of this disease. In the light of the current evidence, pterygium surgery cannot disregard wound coverage with conjunctival autografting or rotational flap combined with adjuvant treatments. The rotational flap technique is associated with shorter surgical time rates and prevents graft displacement and necrosis, given its vascular pedicle. Amniotic membrane may still be reserved in case of great conjunctival defects or insufficient conjunctiva. Repeated subconjunctival antivascular endothelial growth factor injections can be considered as an effective and safe adjuvant treatment. Moreover, management of postoperative pain is crucial. Innovative treatment strategies will probably target different molecular pathways, considering recent findings regarding pterygium pathogenesis, to improve better understanding and develop universally shared guidelines. Great importance shall be dedicated to the identification of novel molecular biomarkers and favoring factors of recurrence, in order to achieve a customized surgical treatment for each patient and obtain maximal reduction of postoperative recurrence.

Corneal Epithelial Damage and Impaired Tear Functions in Patients with Inflamed Pinguecula

Purpose

In this study, we evaluated corneal epithelial integrity and tear film parameters in patients with inflamed pinguecula and compared these findings with their fellow eyes and with healthy controls.

Methods

We evaluated the fluorescein staining properties and performed the tear break-up time (TBUT) test and Schirmer 2 test (ST2) measurements of 32 patients who had symptomatic unilateral inflamed pinguecula and compared the results with their fellow eyes and also with an age- and sex-matched control group.

Results

Twenty-three eyes (72%) in the inflamed pinguecula group and 1 eye (3.1%) in the fellow eyes group had punctate epithelial staining (PES) or epithelial defect on the nasal cornea (p < 0.001). There was no PES or epithelial defect in the control group. Eyes with inflamed pinguecula (n = 32) had lower TBUT and ST2 values compared to the control group (n = 32) (p < 0.001 for both). Fellow eyes (n = 32) also had lower TBUT and ST2 values compared to the control group (p=0.003 for both). There was no difference in the TBUT and ST2 results between the eyes with inflamed pinguecula and fellow eyes (p=0.286 and p=0.951, respectively).

Conclusion

A high percentage of eyes with inflamed pinguecula had nasal corneal epithelial staining or epithelial defect. We also found lower TBUT and ST2 results in eyes with inflamed pinguecula and the fellow eyes compared to the control group. These findings may be important in pathogenesis of pinguecula and pterygium and also in uncovering their relation.

YKL-40 expression in pterygium: a potential role in the pathogenesis

PURPOSE

The aim of the study was to evaluate whether YKL-40 (chitinase 3-like 1 protein) plays a role in pterygium pathogenesis.

METHODS

We included 42 primary pterygium patients and 24 control subjects with normal bulbar conjunctiva in the study. The pterygium patients were classified into the atrophic, fleshy, and intermediate groups according to the Tan classification. We then surgically removed the primary nasal pterygium and normal bulbar conjunctiva from the patients and immunohistochemically investigated YKL-40 expression.

RESULTS

YKL-40 expression was statistically significantly higher in the epithelial, endothelial, and stromal cells of the pterygium tissues than in the control tissues (P = 0.009, P = 0.003, P = 0.002, respectively). There was no significant correlation between the pterygium subgroups and YKL-40 expression (P > 0.05).

CONCLUSIONS

We believe YKL-40 may play a significant role in pterygium pathogenesis.

Current approaches and future directions in the management of pterygium

Pterygium, a common ocular surface disorder, has a complex pathophysiology that may mimic tumorigenesis. There is altered expression of cell cycle/proliferation-related factors in pterygium tissues. Therefore, similar to cancer treatments, the management of pterygium ought to be multifactorial based on the patient's condition. Current therapeutic methods for pterygium are focused on surgical resection in conjunction with antimetabolite use, in addition tissue graft is usually performed in the context of the avoidance of bare sclera. However, future directions in the management of pterygia will likely focus on genetic approaches. This perspective views the pathogenesis of pterygium, its existing therapies as well as current and future challenges in its treatment.

The emerging role of fibrocytes in ocular disorders

The fibrocyte, which was first described in 1994, is a type of circulating mesenchymal progenitor cell in the peripheral blood. Fibrocytes play important roles in chronic inflammation, wound healing, tissue remodeling, and fibrosis. Emerging evidence indicates that fibrocytes are involved in a wide variety of ocular disorders associated with inflammation and fibrosis. In this review, we summarize recent advances regarding the general characteristic profile of fibrocytes, molecular mechanisms underlying the fibrocyte recruitment to target tissues, their differentiation into fibroblasts, and the potential role of fibrocytes in ocular disease. Given the critical role of fibrocytes in ocular disorders, fibrocytes may serve as a promising pharmaceutical target in the development of novel therapeutic strategies to treat ocular inflammation and fibrosis.

Epigenetic Regulation of Myofibroblast Phenotypes in Fibrosis

Purpose of Review

Myofibroblasts are the fundamental drivers of fibrosing disorders; there is great value in better defining epigenetic networks involved in myofibroblast behavior. Complex epigenetic paradigms, which are likely organ and/or disease specific, direct pathologic myofibroblast phenotypes. In this review, we highlight epigenetic regulators and the mechanisms through which they shape myofibroblast phenotype in fibrotic diseases of different organs.

Recent Findings

Hundreds of genes and their expression contribute to the myofibroblast transcriptional regime influencing myofibroblast phenotype. An increasingly large number of epigenetic modifications have been identified in the regulation of these signaling pathways driving myofibroblast activation and disease progression. Drugs that inhibit or reverse profibrotic epigenetic modifications have shown promise in vitro and in vivo; however, no current epigenetic therapies have been approved to treat fibrosis. Newly described epigenetic mechanisms will be mentioned, along with potential therapeutic targets and innovative strategies to further understand myofibroblast-directed fibrosis.

Summary

Epigenetic regulators that direct myofibroblast behavior and differentiation into pathologic myofibroblast phenotypes in fibrotic disorders comprise both overlapping and organ-specific epigenetic mechanisms.

Modulation of Fibroblasts in Conjunctival Wound Healing

Modulating conjunctival wound healing has the potential to improve outcomes after glaucoma filtration surgery and for several ocular disorders, including ocular cicatrial pemphigoid, vernal keratoconjunctivitis, and pterygium. Although anti-inflammatories and antimetabolites have been used with success, these nonspecific agents are not without their complications. The search for novel and more targeted means to control conjunctival fibrosis without such limitations has brought much attention to the regulation of fibroblast proliferation, differentiation, extracellular matrix production, and apoptosis. This review provides an update on where we stand with current antifibrotic agents and outlines the strategies that novel agents use, as they evolve from the bench to the bedside.

Myofibroblast transdifferentiation: The dark force in ocular wound healing and fibrosis

Wound healing is one of the most complex biological processes to occur in life. Repair of tissue following injury involves dynamic interactions between multiple cell types, growth factors, inflammatory mediators and components of the extracellular matrix (ECM). Aberrant and uncontrolled wound healing leads to a non-functional mass of fibrotic tissue. In the eye, fibrotic disease disrupts the normally transparent ocular tissues resulting in irreversible loss of vision. A common feature in fibrotic eye disease is the transdifferentiation of cells into myofibroblasts that can occur through a process known as epithelial-mesenchymal transition (EMT). Myofibroblasts rapidly produce excessive amounts of ECM and exert tractional forces across the ECM, resulting in the distortion of tissue architecture. Transforming growth factor-beta (TGFβ) plays a major role in myofibroblast transdifferentiation and has been implicated in numerous fibrotic eye diseases including corneal opacification, pterygium, anterior subcapsular cataract, posterior capsular opacification, proliferative vitreoretinopathy, fibrovascular membrane formation associated with proliferative diabetic retinopathy, submacular fibrosis, glaucoma and orbital fibrosis. This review serves to introduce the pathological functions of the myofibroblast in fibrotic eye disease. We also highlight recent developments in elucidating the multiple signaling pathways involved in fibrogenesis that may be exploited in the development of novel anti-fibrotic therapies to reduce ocular morbidity due to scarring.

Expression of prostaglandin E2 receptor subtypes in human pterygium and normal conjunctiva: immunohistochemical study

PURPOSE

In the present study, we aimed to evaluate the expression of EP receptors in primary and recurrent human pterygium tissues.

METHODS

Pterygium samples were collected from 65 patients with primary pterygium and 16 patients with recurrent pterygium. Normal conjunctival tissues were collected from nasal interpalpebral area from 17 patients without systemic and any other ocular pathology. Expression of EP receptors was evaluated by immunohistochemistry. The median value for each receptor staining score (RSS) was determined in normal conjunctival specimens. In this study, RSS of > median value was defined as positive staining or high expression and ≤ median value as negative staining or weak expression in specimens. Chi-square test was used for statistical analysis, and p value of less than 0.05 was considered significant.

RESULTS

Stromal expression of EP1 was significantly higher in primary and recurrent pterygium specimens compared to normal conjunctival tissues (p = 0.007 and p = 0.002, respectively). Epithelial expressions of EP2 and EP3 were significantly lower in primary pterygium specimens compared to normal conjunctival tissues (p = 0.005 and p < 0.0001, respectively), and stromal expressions were insignificant. Stromal expression of EP4 was significantly higher in primary and recurrent pterygium specimens compared to normal conjunctival tissues (p = 0.002 and p = 0.012, respectively).

CONCLUSIONS

Expression of EP receptors has been up- or downregulated in primary and recurrent pterygium tissues, and these receptors may play a role in formation and recurrence of pterygium.

Overexpression of low-density lipoprotein receptors stimulated by vascular endothelial growth factor in fibroblasts from pterygium

The activation of subconjunctival fibroblasts is believed to be responsible for the pathogenesis of pterygium. Vascular endothelial growth factor (VEGF) appears to be the most potent stimulator of formation and progression of pterygium. Pterygium excision is a common procedure, although the recurrence rates remain high. Various postoperative adjuvant therapies are now attempted to lower the recurrence rate, with severe side effects. To offer a greater therapeutic effect and lower side effects, it's necessary to discover a constant nanoparticle drug delivery targeting to subconjunctival fibroblasts in pterygium (PSFs). This study was designed to investigate the expression of low-density lipoprotein receptor (LDLr) stimulated by VEGF in PSFs. We found that after exposure to VEGF, mRNA and protein levels of LDLr were both increased significantly in PSFs, assessed using relative quantitative real-time RT-PCR and Western blot. Moreover, it's demonstrated that the expression of LDLr were positively correlated with the cells proliferation. Uptake of DiI-LDL via live PSFs was increased with time, estimated by confocal microscopy. The protein expression of LDLr in pterygium subconjunctival tissues was significantly higher than in normal subconjunctival tissues. These results suggest that LDLr in the activated PSFs may become a novel target receptor for controlled drug delivery to lower postsurgical recurrence rate.

Identification of pterygium-related mRNA expression profiling by microarray analysis

PurposePterygium is a common degenerative and proliferative disease of the ocular surface. In some severe cases, pterygium may lead to irregular corneal astigmatism and corneal stromal scarring with visual impairment. The proliferative capacities of pterygial cells make them appear similar to tumorigenesis. Although considerable progress has been made towards understanding the etiology of the disease, the pathogenesis of pterygium has not been completely understood. In our previous study, we constructed pterygium-related lncRNA libraries by using microarray to investigate the potential roles of lncRNAs in pterygium. In this study, our objective was to explore the role of mRNA in pterygium.Patients and methodsIn this study, we constructed pterygium-related mRNA libraries by using microarray to investigate the potential roles of mRNAs in pterygium. Quantitative real-time PCR (qRT-PCR) was performed to validate some of the deregulated mRNAs in 10 patients.ResultsA total of 1485 upregulated and 2978 downregulated mRNAs were identified in pterygium tissues compared with paired adjacent normal conjunctival tissues (log fold change>2.0). qRT-PCR was performed to validate four overregulated and two underregulated mRNAs in 10 patients.ConclusionsOur results reveal differentially expressed mRNAs in pterygium and suggest that mRNAs may be the novel molecular targets for therapy of pterygium.