Epidermal growth factor is a constant component of normal human tear fluid

Classic lattice corneal dystrophy: a brief review and summary of treatment modalities

PURPOSE

To provide a brief summary and comparison of the most recent literature on available and theorized treatment modalities for classic lattice corneal dystrophy (LCD). This paper aims to support practitioners in their management of this disease.

METHODS

A search was carried out on available literature through PubMed and Google Scholar of English language articles up to January 2023 that relate to the treatment of LCD. Due to scarcity of literature regarding specific novel therapies for LCD, results from other corneal pathologies (granular corneal dystrophy, corneal scarring) are sometimes included for contrast, which is clearly denoted.

RESULTS

LCD is a slowly progressive disease that leads to recurrent epithelial corneal erosions, stromal haze, corneal opacification, substantial discomfort, and visual impairment. Due to its autosomal-dominant inheritance pattern, this disease can persist throughout ancestral lines and requires consistent treatment and follow-up. An optimal management plan is necessary to (1) prolong years of life with best achievable visual acuity; (2) treat painful recurrent corneal erosions as they occur; (3) ensure proper follow-up throughout the life of a patient, as well as monitor at-risk offspring; and (4) monitor efficacy of treatment.

CONCLUSIONS

This paper addresses (1) treatment for early disease including corneal epithelial debridement, photo therapeutic keratectomy (PTK), femtosecond laser-assisted lamellar keratectomy (FLK), and others; (2) treatment for late disease including full thickness keratoplasties and anterior lamellar keratoplasties; and (3) potential future treatment considerations including a wide variety of topical/systemic, genetic, and regenerative approaches.

Hyperstable EGF-like bleogen derived from cactus accelerates corneal healing in rats

Corneal scarring reduces corneal transparency, compromises vision, and is a major cause of vision loss worldwide. Epidermal growth factor (EGF), which is the prototypic member of the EGF receptor (EGFR) agonists, is present in tears to provide repair and regeneration. Recently, we discovered bleogen pB1 in the cactus plant Pereskia bleo and showed that it is a non-canonical and hyperstable EGFR agonist with EGF-like wound healing properties for diabetic rats. Here, we apply bleogen pB1 to accelerate corneal wound healing in rats. To assess the corneal healing effects of bleogen pB1, we induced an acute alkali burn to the right eye of male Wistar rats. After five consecutive ophthalmic applications, fluorescein staining and opacity scores of the bleogen pB1-treated, and the positive control EGF-treated groups improved significantly compared to the saline control group. Immunohistochemical analyses revealed that infiltrated CD68+ macrophages and the expression of the myofibroblast marker alpha smooth muscle actin (α-SMA) were significantly decreased in the bleogen pB1- and the EGF-treated groups. By employing a differential gene expression analysis of bleogen pB1- and EGF-treated keratinocytes through RNA-seq, we demonstrated that bleogen pB1 or EGF treatments can affect the expression of genes associated with inflammatory responses and extracellular matrix remodeling. Taken together, our results indicate that the plant-derived EGFR agonist bleogen pB1 can produce similar effects to those of EGF in accelerating corneal wound healing as well as in reducing persistent inflammation and myofibroblast accumulation in the cornea.

Management of Ocular Surface Disease in Glaucoma: A Survey of Canadian Glaucoma Specialists

PRéCIS:: Ocular surface disease (OSD) in glaucoma is an area for improvement in the management of patients with glaucoma. This study explores the knowledge of glaucoma subspecialists toward OSD in glaucoma, then provides a suggested treatment algorithm.

PURPOSE

To assess the attitudes, knowledge, and level of comfort of Canadian glaucoma specialists with respect to the assessment and management of OSD among patients with glaucoma.

METHODS

Ophthalmologist members of the Canadian Glaucoma Society with fellowship training in glaucoma were contacted to participate in this cross-sectional survey study. Responses were recorded to statements regarding attitudes toward OSD in glaucoma, and assessment and management modalities. These were recorded primarily in the form of a Likert scale rated 1 to 7 from "strongly disagree" to "strongly agree." Descriptive statistics were generated, and mean and SD for responses on Likert scales.

RESULTS

Thirty-six responses were included. All respondents agreed that comprehensive management of OSD could improve quality of life, 97% agreed it could lead to better glaucoma outcomes, whereas only 22% agreed it is presently being adequately managed in glaucoma practices. Respondents were asked to list all treatment modalities they felt knowledgeable about, ranging from 100% for optimizing topical glaucoma therapies to 31% for serum tears. Nearly all respondents (92%) agreed that a suggested algorithm for the treatment of OSD in glaucoma could improve their approach to management.

CONCLUSION

OSD is a common comorbidity of glaucoma. Although respondents overwhelmingly agreed that comprehensive management of OSD may lead to improved quality of life and glaucoma-related outcomes, only a small percentage felt it was presently adequately managed. Increasing knowledge related to the assessment and management of OSD in glaucoma may in the future improve patient care.

Biological functions of tear film

Tears have a vital function to protect and lubricate the ocular surface. Tear production, distribution and clearance is tightly regulated by the lacrimal functional unit (LFU) to meet ocular surface demands. The tear film consists of an aqueous-mucin layer, containing fluid and soluble factors produced by the lacrimal glands and mucin secreted by the goblet cells, that is covered by a lipid layer. The array of proteins, glycoproteins and lipids in tears function to maintain a stable, well-lubricated and smooth optical surface. Tear factors also promote wound healing, suppress inflammation, scavenge free radicals, and defend against microbial infection. Disease and dysfunction of the LFU leads to tear instability, increased evaporation, inflammation, and blurred and fluctuating vision. The function of tear components and the consequences of tear deficiency on the ocular surface are reviewed.

Compensatory increases in tear volume and mucin levels associated with meibomian gland dysfunction caused by stearoyl-CoA desaturase-1 deficiency

The stearoyl-CoA desaturase (SCD) family of enzymes catalyzes monounsaturated fatty acid synthesis by inserting a cis double bond at the Δ9 position of saturated fatty acids. Disruption of these enzymes has been reported to induce a severe dry skin phenotype. Since lipid abnormalities in the meibomian glands have been associated with dry eye, we analyzed selected eye tissues contributing to tear volume and composition in genetically SCD-1-deficient mice (SCD-1 KO), including the lacrimal glands and conjunctiva. Previous histopathological analysis had revealed atrophy and loss of meibomian glands; taken together with the increased goblet cell and MUC5AC expression in the conjunctiva reported here, these findings suggest that the tear volume and mucin levels secreted are enhanced in the absence of lipid secretion as a compensatory mechanism. The expression of lipid metabolism genes in lacrimal glands was decreased in SCD1 KO mice. Thus, these results provide new pathophysiological mechanisms to pursue with regard to meibomian gland dysfunction. In addition, lack of SCD-1 causes a compensatory increase in the tear volume and mucin levels associated with changes in expression of lipid metabolism genes. These results may be useful as a new concept for dry eye treatment strategies.

Topical N-acetylcysteine Reduces Interleukin-1-alpha in Tear Fluid after Laser Subepithelial Keratectomy

Purpose

To evaluate the effect of topical N-acetylcysteine (NAC) on interleukin 1-alpha (IL-1α) levels in tear fluid after myopic laser subepithelial keratectomy (LASEK) and its possible role in modulating corneal wound healing.

Methods

Twenty-six eyes of 13 patients who underwent myopic LASEK were divided into 2 groups. Group 1 (n=10 eyes) was used as a control group. All patients received topical lomefloxacin and dexamethasone postoperatively. Additionally, patients in Group 2 received topical NAC for 1 month postoperatively. Tear fluid samples were collected with microcapillary tubes preoperatively, on the first and on the fifth postoperative day, and the release of IL-1α in tear fluid was calculated. Haze grading and confocal microscopic examination were performed at 1 and 3 months postoperatively.

Results

The mean IL-1-α release values were 0.285±0.159 pg/min in Group 1 and 0.235±0.142 pg/min in Group 2 preoperatively. In Group 1, the values were 0.243±0.155 pg/min on day 1 and 0.164±0.125 pg/min on day 5. In Group 2, the mean IL-1α release values were 0.220±0.200 pg/min on day 1 and 0.080±0.079 pg/min on day 5. The difference between the groups was significant only for day 5 (p<0.05). Mean corneal haze score and grey scale value in confocal microscopy were significantly higher (p<0.05) in Group 1 at 1 month. However, at 3 months there was no difference between groups (p>0.05).

Conclusions

NAC seems to have an additive effect to steroids in suppressing IL-1α levels in tear fluid and may be clinically advantageous in modulating corneal wound healing during the early postoperative period after LASEK.

Irritable bowel syndrome might be associated with dry eye disease

Background

A possible association between dry eye disease (DED) and irritable bowel syndrome (IBS) has been hypothesized based on the fact that they both share an inflammatory pathogenesis.

Methods

Ninety-five patients with IBS and 276 healthy controls were enrolled in the study. All patients answered a questionnaire regarding DED symptoms and had a complete ophthalmic examination. DED signs were evaluated using Schirmer’s 1 and tear break-up time (tBUT) tests in both groups.

Results

Female IBS participants presented significantly lower Schirmer’s test and tBUT (P=0.002 and P<0.001 respectively) than controls. Both diagnostic tests in male IBS patients were also significantly lower than in controls (P<0.001). 72% of IBS patients gave at least 3 positive answers to the questionnaire compared with 42% of the control group (P<0.01).

Conclusion

Our results suggest a correlation between IBS and DED. DED symptoms can cause further complications in patients with IBS, and should be considered in their management. However, further research is needed to establish a possible pathophysiologic association.

Autologous Platelet-rich Plasma Eye Drops in the Treatment of Recurrent Corneal Erosions

PURPOSE

To evaluate the effect of platelet-rich plasma (PRP) eye drops in the treatment of recurrent corneal erosions (RCE).

METHODS

A total of 47 eyes were included in this retrospective study. Clinical records of 20 consecutive patients with RCE who had been treated with conventional lubricant eye drops (conventional treatment group) from June 2006 to December 2008 and 27 consecutive patients treated with autologous PRP eye drops in addition to lubricant eye drops (PRP eye drops treated group) from January 2009 to September 2014 were reviewed. Major and minor recurrences were recorded and compared between two groups.

RESULTS

This study included 31 men and 16 women. The mean age was 44.5 ± 14.5 years (range, 19 to 86 years), and the mean follow-up duration was 14.9 ± 14.4 months (range, 6 to 64 months). Of the 27 cases in the PRP eye drops treated group, there were seven major recurrences in six eyes (22.2%) and ten minor recurrences in seven eyes (25.9%). In contrast, 16 eyes (80.0%) from the 20 patients in the conventional lubricant eye drops treated group had major recurrences, and all patients in this group reported minor recurrences. The mean frequency of recurrence was 0.06 ± 0.08 per month in the PRP eye drops treated group and 0.39 ± 0.24 per month in the conventional treatment group (p = 0.003). No side effects were noted in any of the patients over the follow-up period.

CONCLUSIONS

The use of PRP eye drops for the treatment of RCE was shown to be effective in reducing the recurrence rate without any significant complications.

Ocular graft-versus-host disease

PURPOSE OF REVIEW

This review was carried out to study the frequency, and severity of ocular surface involvement at the setting of allogeneic hematopoietic stem cell transplantation and subsequent graft-versus-host disease (GVHD) and evaluate the clinical outcomes of newer treatments.

RECENT FINDINGS

Ocular involvement has been reported in 60-90% of patients with chronic GVHD. Although dry eye is the most frequent finding occurring in the great majority of patients (up to 90%), posterior segment complications are also not infrequent, seen in 12.8% of patients after bone marrow transplantation. Anti-inflammatory treatments particularly T-cell suppressants seem to have a beneficial effect in managing GVHD. Corticoteroids, calcineurin inhibitors, such as cyclosporine and tacrolimus, as well as antifibrotic agents such as tranilast are available options for topical application. Cyclosporine ophthalmic drop seems to be a well tolerated and effective treatment modality; favorable results have been demonstrated with increased dosage.

SUMMARY

GVHD is an increasingly frequent cause of ocular surface morbidity with the potential of visual loss from corneal involvement. Early diagnosis and aggressive local as well as systemic treatment can be vision saving.

Contact lens wearing and chronic cigarette smoking positively correlate with TGF-β1 and VEGF tear levels and impaired corneal wound healing after photorefractive keratectomy

PURPOSE

To study the correlation of gender, contact lens (CL) wearing, chronic drinking and chronic smoking with wound healing cytokine levels and corneal recovery after photorefractive keratectomy (PRK).

MATERIALS AND METHODS

One hundred and twenty-eight age-matched patients (180 eyes) undergoing PRK were enrolled. PDGF, EGF, VEGF, HGF and TGF-β(1) protein levels were measured in tears by enzyme-linked immunosorbent assay either preoperatively or 2, 7 and 15 days after PRK. Patients were seen between one day and five days postoperatively for the evaluation of epithelial healing. Delayed re-epithelialization was defined as healing after day 5. All patients were followed for haze formation for a minimum of three months.

RESULTS

All cytokines increased significantly during the first two postoperative days (p < 0.001). PDGF, EGF, HGF decreased to the preoperative levels by day 7, whereas TGF-β1 and VEGF remained elevated over the entire period of observation of 15 days, although to a lesser extent than the second day after surgery, in CL-wearers and smokers, respectively (p < 0.01). The Pearson correlation analysis showed that: (i) CL-wearing positively correlated with TGF-β1 amounts, while chronic smoking positively correlated with VEGF production; (ii) CL-wearing and TGF-β1 amount were found to be associated with early haze formation, whereas chronic smoking and VEGF level with delayed re-epithelialization. No association was found between gender or alcohol consumption and cytokine levels or wound healing.

CONCLUSIONS

Our findings highlight for the first time the important role that cigarette smoking and CL wearing may have in altering the tear cytokine network and impairing corneal epithelial wound repair after surgical injury.

Treatment of corneal defects with delayed re-epithelization with a medical device/drug delivery system for epidermal growth factor

BACKGROUND

  Human recombinant epidermal growth factor has been shown to be effective in corneal healing when applied topically. The purpose of this preliminary study was to observe whether re-epithelization occurred in patients with non-healing corneal defects treated with a bandage contact lenses impregnated with epidermal growth factor.

DESIGN

  Prospective non-comparative interventional case series study. Epidermal growth factor-impregnated bandage contact lenses (created through passive transfer of epidermal growth factor into hydrogel contact lenses of high water content) were used to passively release epidermal growth factor to the corneal surface of the damaged eye.

PARTICIPANTS

  Nine clinical patients who presented for tertiary care at the University of British Columbia Eye Care Centre at Vancouver General Hospital.

METHODS

  All patients had clinically significant delayed corneal re-epithelization that had not healed despite standard treatments including conventional bandage contact lenses and topical medications. Causes of delayed re-epithelization varied from corneal injuries (e.g. alkali burns, recurrent corneal erosions) to recent corneal surgery (photorefractive keratectomy, phototherapeutic keratectomy, penetrating keratoplasty).

MAIN OUTCOME MEASURES

  Closure of wounds.

RESULTS

  Re-epithelialization was seen in the corneas of seven of the nine patients within 8 days after insertion of the epidermal growth factor-treated bandage contact lens into the damaged eye. The drug delivery system appeared to be most effective in non-inflamed corneas.

CONCLUSIONS

  Preliminary results indicate that bandage contact lenses impregnated with epidermal growth factor may be helpful in promoting re-epithelization in corneas with delayed healing. Efficacy appears to be reduced for vascularized and significantly inflamed corneas.

Posology, efficacy, and safety of epidermal growth factor eye drops in 305 patients: logistic regression and group-wise odds of published data

The aim of this article is to investigate clinical research on indications, posology, efficacy, and safety of epidermal growth factor (EGF) eye drops in the treatment of some human corneal disorders. Methods used include systematic search and selection of series of cases and clinical trials in Medline database up to January 2012, kappa index (K) to validate retrieval information, cumulative Mantel-Haenszel-stratified meta-analysis, 2×2 contingency table of randomized EGF-vehicle-controlled treated groups, and statistical program SPSSv12. Our results indicate that EGF eye drops appear to be a very effective treatment of acute heterogeneous corneal diseases, without significant adverse effects, with a 86.8% clinical efficacy reported by authors, a 98% (P<0.05) probabilistic expected efficacy, and 51.3 (17.4-148.7 confidence interval 95%; P<0.05) odds ratio EGF/vehicle. However, clinical trials are scarce, with low sample sizes and serious inconsistencies in EGF posology. EGF eye drops (50-1,000 ng, 2-3 times/day) could be a useful treatment for promoting postoperative refractive surgery, reversing cases of keratopathy secondary to systematic EGF receptor inhibitors, diabetic keratopathy, and other corneal and conjunctival disorders.

Autologous platelet lysate for treatment of refractory ocular GVHD

Current treatment of ocular GVHD (oGVHD), represented by systemic immunosuppressive regimens and local therapies (mainly artificial tears and corticosteroids), gives unsatisfactory results. We investigated the safety and efficacy of autologous plasma rich in PDGFs to treat oGVHD unresponsive to standard medications. A total of 23 patients with refractory oGVHD (grade II-IV) unresponsive to standard therapy were treated with autologous plasma rich in PDGFs eye drops (PRGD) four times/day for 6 months. Symptoms and signs (best visual acuity, Schirmer's test and tear break up time (TBUT), evaluation of the anterior segment and fluorescein and lissamine staining) were always assessed by the same ophthalmologist. Patients were defined as 'responders' when showing improvement for total complaints and at least one sign. At 30 days of treatment, 17 patients (73.9%) were classified as responders. The symptom that improved most was photophobia (improved in 19 patients, 82.6%). TBUT improved in 20 patients (86.9%) and anterior segment score in 19 patients (82.6%). Response was maintained over time. No serious adverse events occurred. PRGD proved to be safe and effective in treating oGVHD and may be a valid treatment option from the early stages of the disease to avoid irreversible ocular damage.

Direct imaging of RAB27B-enriched secretory vesicle biogenesis in lacrimal acinar cells reveals origins on a nascent vesicle budding site

This study uses YFP-tagged Rab27b expression in rabbit lacrimal gland acinar cells, which are polarized secretory epithelial cells, to characterize early stages of secretory vesicle trafficking. Here we demonstrate the utility of YFP-Rab27b to delineate new perspectives on the mechanisms of early vesicle biogenesis in lacrimal gland acinar cells, where information is significantly limited. Protocols were developed to deplete the mature YFP-Rab27b-enriched secretory vesicle pool in the subapical region of the cell, and confocal fluorescence microscopy was used to track vesicle replenishment. This analysis revealed a basally-localized organelle, which we termed the "nascent vesicle site," from which nascent vesicles appeared to emerge. Subapical vesicular YFP-Rab27b was co-localized with p150(Glued), a component of the dynactin cofactor of cytoplasmic dynein. Treatment with the microtubule-targeted agent, nocodazole, did not affect release of mature secretory vesicles, although during vesicle repletion it significantly altered nascent YFP-Rab27b-enriched secretory vesicle localization. Instead of moving to the subapical region, these vesicles were trapped at the nascent vesicle site which was adjacent to, if not a sub-compartment of, the trans-Golgi network. Finally, YFP-Rab27b-enriched secretory vesicles which reached the subapical cytoplasm appeared to acquire the actin-based motor protein, Myosin 5C. Our findings show that Rab27b enrichment occurs early in secretory vesicle formation, that secretory vesicles bud from a visually discernable nascent vesicle site, and that transport from the nascent vesicle site to the subapical region requires intact microtubules.

Pharmacological cholinergic blockade stimulates inflammatory cytokine production and lymphocytic infiltration in the mouse lacrimal gland

PURPOSE

To investigate the effects of cholinergic blockade on inflammatory cell infiltration and cytokine production in the mouse lacrimal gland (LG).

METHODS

C57BL/6 mice were untreated (UT) or received subcutaneous injections of either scopolamine hydrobromide (SCOP; 0.5 mg/0.2 mL) or saline (SAL) four times daily for 2 or 5 days (2D, 5D). This was followed by a 7-day rest period in separate groups. Tear volume (cotton thread) and tear epidermal growth factor (EGF, by ELISA) concentrations were measured. Extraorbital LGs were surgically excised and sectioned or lysed for gene expression analysis. Immunohistochemistry evaluated immunophenotype of infiltrating cells. Expression of EGF and T helper (Th)-1, -2, and -17-associated cytokines in LGs was evaluated by real-time PCR. Goblet cell density was evaluated in periodic acid Schiff-stained conjunctival sections.

RESULTS

Tear volume and EGF protein levels were significantly reduced in SCOP5D mice compared with controls, indicating that cholinergic blockade decreased LG secretory function. LGs of SCOP2D and SCOP5D mice showed an increased density of CD4(+), CD11c+, CD11b+, and myeloperoxidase+ cells compared with UT controls. At day 5, these cells were significantly elevated compared with SAL-treated counterparts. Elevated levels of IL-17A, IL-17R, IFN-γ, IL-12Rβ1, IL-2, IL-13, IL-6, IL-1β, and TNF-α transcripts were noted in SCOP2D mice and IFN-γ, TGF-β1, and IL-18R transcripts in SCOP5D mice.

CONCLUSIONS

Pharmacological blockade of lacrimal secretion induced a significant CD4(+) infiltration in the LG, mimicking Sjögren's syndrome. The mRNA expression profile revealed elevations of a mix of inflammatory cytokines and Th-1-associated factors.

Rab27b regulates exocytosis of secretory vesicles in acinar epithelial cells from the lacrimal gland

Tear proteins are supplied by the regulated fusion of secretory vesicles at the apical surface of lacrimal gland acinar cells, utilizing trafficking mechanisms largely yet uncharacterized. We investigated the role of Rab27b in the terminal release of these secretory vesicles. Confocal fluorescence microscopy analysis of primary cultured rabbit lacrimal gland acinar cells revealed that Rab27b was enriched on the membrane of large subapical vesicles that were significantly colocalized with Rab3D and Myosin 5C. Stimulation of cultured acinar cells with the secretagogue carbachol resulted in apical fusion of these secretory vesicles with the plasma membrane. Evaluation of morphological changes by transmission electron microscopy of lacrimal glands from Rab27b(-/-) and Rab27(ash/ash)/Rab27b(-/-) mice, but not ashen mice deficient in Rab27a, showed changes in abundance and organization of secretory vesicles, further confirming a role for this protein in secretory vesicle exocytosis. Glands lacking Rab27b also showed increased lysosomes, damaged mitochondria, and autophagosome-like organelles. In vitro, expression of constitutively active Rab27b increased the average size but retained the subapical distribution of Rab27b-enriched secretory vesicles, whereas dominant-negative Rab27b redistributed this protein from membrane to the cytoplasm. Functional studies measuring release of a cotransduced secretory protein, syncollin-GFP, showed that constitutively active Rab27b enhanced, whereas dominant-negative Rab27b suppressed, stimulated release. Disruption of actin filaments inhibited vesicle fusion to the apical membrane but did not disrupt homotypic fusion. These data show that Rab27b participates in aspects of lacrimal gland acinar cell secretory vesicle formation and release.

Current insights into ocular graft-versus-host disease

PURPOSE OF REVIEW

To update our knowledge on hematopoietic stem cell transplantation (SCT) and graft-versus-host disease (GVHD) and summarize the current treatment options for ocular GVHD.

RECENT FINDINGS

Allogeneic (allo)-SCT represents a treatment option for a number of hematological malignancies and bone marrow disorders; the indications for this procedure are still increasing. Ocular GVHD develops in 40-60% of patients after allo-SCT, can cause severe ocular surface disease and has a negative impact on quality of life. There are no widely accepted guidelines for the treatment of ocular GVHD. In addition to the usual treatment with artificial tears, topical steroids, punctal occlusion and contact lenses, recent treatment options include anti-inflammatory medications including topical cyclosporine A and tacrolimus. Unfortunately, none of the treatment regimens are completely satisfactory and systematic data on the efficacy of these agents are lacking. The preventive treatment possibilities for ocular GVHD have not been defined.

SUMMARY

This review summarizes current data on ocular GVHD and focuses on novel treatment options for this severe ocular disorder. More data on the impact of ocular GVHD and the development of therapeutic and preventive measures are needed.

Effects of growth factors on corneal wound healing

Healing of ocular surface wounds is a complex process involving migration, mitosis, and differentiation of epithelial and stromal cells. Endogenously produced peptide growth factors such as epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), or transforming growth factor beta (TGF-beta) may play key roles in the natural wound healing process. Lacrimal gland cells were reported to synthesize and secrete EGF into tear fluid where it may enhance healing of corneal epithelial and stromal injuries by an exocrine pathway. EGF stimulated DNA synthesis of epithelial cells and stromal fibroblasts in culture, stimulated synthesis of fibronectin by epithelial cells and was chemotactic for human epithelial and stromal cells. Human corneal epithelial cells also synthesized TGF-alpha which may influence epithelial cells by an autocrine pathway. TGF-beta, which is a potent inducer of lysyl oxidase mRNA levels in cultures of human scleral fibroblasts, may be the factor most responsible for inducing synthesis of corneal extracellular matrix components after an injury. Treatment of epithelial injuries ocular surface wounds with exogenous peptide growth factors also accelerated healing in rabbits and primates. Treatment of severe ocular surface injuries caused by alkali with a combination of EGF, fibronectin, a synthetic collagenase inhibitor, and Aprotinin significantly blocked ulceration and enhanced epithelial regeneration. Clinical trials of topical treatment of EGF for ocular surface wounds suggest that peptide growth factors may be a valuable adjuvant for treatment of ocular surface wounds.

Molecular and cellular responses of the corneal epithelium to wound healing

The corneal epithelium responds rapidly to injury, repairing defects with a layer of cells that covers the denuded corneal surface and prevents infection and loss of vision. After a wound, reorganization of the remaining epithelial cells occurs over several hours, resulting in the formation of a migratory leading edge. However, expression of genes such as c-fos occurs within minutes of wounding. This early expression may be important for directing epithelial reorganization and the later mitotic burst. Our results show that receptors for epidermal growth factor are upregulated in the migratory cell population. Proliferation through a mitotic burst was observed in cells surrounding the original wound margin after 36 hours. The interaction between gene expression and cell surface receptors for growth factors and cell proliferation suggests that wound healing occurs in a complex, but tightly controlled process in the corneal epithelium.

Allogeneic serum eye drops for the treatment of severe dry eye in patients with chronic graft-versus-host disease

PURPOSE

To describe the use of allogeneic serum eye drops to treat 2 patients with chronic graft-versus-host disease (GVHD)-induced severe ocular surface disease.

METHODS

Small case series.

RESULTS

Conventional therapy failed to control the ocular symptoms of 2 patients with GVHD who presented with severe dry eye syndrome. Because autologous serum was unavailable in these cases, we used allogeneic serum eye drops as an alternate option for treating their ocular surface disease. Both donors had serologic tests performed before donation. Use of the allogeneic serum eye drops had a beneficial clinical effect, with marked attenuation of the patients' symptoms. This therapy proved to be safe during 10 months of treatment.

CONCLUSIONS

Allogeneic serum eye drops may be a good alternative treatment for patients with severe dry eyes caused by GVHD.

Graft failure: II. Ocular surface complications

Risk factors for corneal transplantation failure include both immunologic factors, such as graft rejection, corneal neovascularization, and peripheral anterior synechiae, as well as non-immunologic factors, such as ocular surface disorders (OSD) and glaucoma. This review highlights the necessity of having healthy ocular surface epithelia, tears, and eyelids. It presents different types of OSD, their underlying pathology, and their impact on native cornea and corneal grafts. In addition, a range of proposed donor and surgical factors influencing surface integrity following corneal transplant are addressed. Current medical and surgical research, both pre- and post-operative that promise to further improve the outcome of corneal grafts in the context of OSD are discussed.

Autologous serum Therapy of the ocular surface with Novel Delivery by Platelet Concentrate Gel

Application of autologous serum to treat a multitude of ocular surface diseases and conditions is a relatively new technique that has gained popularity over the past 10 years. This review focuses on the use of topical autologous serum and a new platelet gel delivery technique that utilizes autologous platelet concentrate mixed with calcium chloride and thrombin for gelling serum, which can then be applied easily to the corneal surface. Residual platelet serum concentrate can be mixed with artificial tears that are capable of gelling in a 25% concentrate, which is then used by the patient postoperatively. A review of the literature identifies various concentrations of autologous serum, frequency of application, and storage criteria.

Assessment of stromal keratocytes and tear film inflammatory mediators during extended wear of contact lenses

PURPOSE

To monitor quantitative changes in stromal keratocyte density and the level of tear film inflammatory mediators following extended contact lens wear.

METHODS

Twenty-two subjects aged 32 +/- 11 years participated in this cross-sectional study. Eleven subjects had worn silicone hydrogel (Si-H) lenses on a 30-day continuous wear basis for 12 months. Eleven subjects had worn rigid gas permeable lenses on the same basis for 12 months. Eleven age-matched control subjects were also recruited. Ultrasound pachometry, confocal microscopy, and tear fluid sample collection were performed on all subjects. Tear samples were assayed for epidermal growth factor (EGF), hepatocyte growth factor (HGF) and interleukin (IL)-8.

RESULTS

Corneal thickness was similar for all subject groups. Total keratocyte density was not different between the 3 groups; however, keratocyte density was lower for rigid lens wearers in the anterior to mid stroma and lower for Si-H lens wearers in the posterior stroma compared with control subjects. Rigid lens wearers exhibited an irregular keratocyte distribution across the corneal stroma. EGF concentration and rate of release was greater in the tears collected from the rigid lens wearers and Si-H lens wearers, and IL-8 concentration was higher in the samples collected from the rigid lens wearers compared with the samples collected from the control subjects.

CONCLUSIONS

Mechanical stimulation of the corneal surface due to the physical presence of a contact lens and the consequent release of inflammatory mediators may account for a loss or redistribution of keratocytes.

Use of Autologous Serum in Corneal Epithelial Defects Post-Lamellar Surgery

PURPOSE

To evaluate the efficacy of an autologous serum treatment of post-LASIK (laser in situ keratomileusis) corneal epithelial defects in a rabbit model.

METHODS

Five milliliters blood samples from 10 New Zealand rabbits were obtained by venepuncture. The serum was aseptically separated and diluted with saline solution to 20%. The final preparation was placed into 3-mL bottles with ultraviolet protection and maintained at 4 degrees C. Corneas were de-epithelialized using a 7-mm optical zone marker. A 160-microm thick flap was created in both eyes of all rabbits using an automatic corneal shaper microkeratome. Right eyes were treated with serum drops 6 times per day. Left eyes were treated with preservative-free artificial tears. Vital staining of the ocular surface and the area of corneal epithelial defect was measured daily for 1 week. Rabbits were humanely euthanized at postoperative day 7, and corneas were fixed and sectioned. Hematoxylin and eosin staining and immunohistochemical analysis were performed.

RESULTS

Corneas treated with autologous serum had a statistically significant increase in the epithelial healing rate compared with those treated with artificial tears. Serum-treated corneas showed significantly less terminal transferase-mediated dUTP nick-end labeling (TUNEL) staining in the interface, minimal inflammatory cell infiltration, and less induced synthesis of stromal chondroitin sulfate than did corneas treated with preservative-free artificial tears.

CONCLUSIONS

Treatment with autologous serum could be an efficient way to provide essential components to the ocular surface in the treatment of post-LASIK epithelial defects. Autologous serum induces faster epithelial healing than do artificial tears, leading to (1) a decrease in keratocyte apoptosis and migration of fibroblasts and myofibroblasts in the wound site, (2) a decrease in the migration of inflammatory cells, and (3) a consequent inhibition of cytokine release. This treatment could improve long-term refractive results post-LASIK.

Differential effects of the EGF family of growth factors on protein secretion, MAPK activation, and intracellular calcium concentration in rat lacrimal gland

The purpose of this study was to investigate the expression of the EGF family of growth factors and EGF receptor subtypes (ErbB1-4) present in lacrimal gland and determine the effects of these growth factors on different functions of rat lacrimal gland. RT-PCR was used to detect mRNA expression in the lacrimal gland of selected members of the EGF family of growth factors, namely EGF, transforming growth factor alpha (TGF-alpha), heparin-binding EGF (HB-EGF), and heregulin. The presence of ErbB receptors was investigated by immunofluorescence microscopy and western blot analysis. The effects of EGF, TGF-alpha, HB-EGF, and heregulin on protein secretion from lacrimal gland acini were examined using a fluorescent assay for peroxidase, a marker of protein secretion. Fura-2 tetra-acetoxymethyl ester was used to measure the effects of the growth factors on intracellular [Ca2+] ([Ca2+]i) in acini. MAPK activation in acini by these growth factors was also examined by western blot analysis using antibodies specific to phosphorylated p42/44 MAPK and total p42 MAPK. Rat lacrimal gland expressed EGF, TGF-alpha, HB-EGF, and heregulin mRNA, and all four ErbB receptors were present in the lacrimal gland as detected by western blot analyses. ErbB 1 and ErbB2 were located in basal and lateral membranes of acinar and ductal cells. The location of ErbB3 could not be determined while ErbB4 was found in ductal cells. Heregulin (10(-7) m) significantly increased protein secretion in lacrimal gland acini whereas all growth factors tested significantly increased [Ca2+]i at 10(-7) m. TGF-alpha (10(-9) m), heregulin (10(-7) m), EGF (10(-7) m), and HB-EGF (10(-7) m) significantly increased the amount of phosphorylated MAPK in lacrimal gland acini. We conclude that all members of the EGF family of growth factors studied are synthesised in rat lacrimal gland, could activate all four ErbB receptors that are present in this tissue, and differentially activate lacrimal gland functions.

[Sterility of non-preserved autologous serum drops for treatment of persistent corneal epithelial defects]

PURPOSE

To investigate the sterility of non-preserved autologous serum drops in hospitalized patients with persistent corneal epithelial defects.

METHODS

Thirty patients with persistent corneal epithelial defects (aged between 28 and 85, mean 67+/-14 years) were treated with autologous serum drops in five different wards of a university eye hospital between October 2001 and March 2002. After centrifugation of freshly collected autologous blood, the serum was stored in sterile drop bottles at refrigerator temperature (7 degrees C) and applied undiluted every 1 or 2 h up to 7 days. Using blood, chocolate, endo, and Sabouraud agar media, we assessed the sterility of autologous serum drops on the day before application and on the 4th and 7th days. Examinations performed on the 1st and 4th days included 40 autologous serum drops each and on the 7th day 120 samples (40 serum drops, 40 bottle tops, and 40 bottle bottoms). The agar media for bacterial examination were read after 48 h of incubation time, and those for fungal examination were read after 21 days. All patients had received topical autologous serum therapy and prophylactic antibiotic drops for at least 7 days.

RESULTS

The time period of autologous serum treatment ranged from 7 to 28 (10+/-5) days. On the 1st and 4th days autologous serum drops were sterile. On the 7th day, 3 of 40 (7.5%) samples were contaminated with Staphylococcus epidermidis. Two of these contaminations were due to a combined serum drop and bottle top contamination (5%). A third case resulted from additional bottle bottom contamination (2.5%). None of the samples examined showed signs of fungal infection. During application of autologous serum as well as during the follow-up period no patient showed any symptoms of ocular infection.

CONCLUSIONS

The application of autologous serum has proven to be a practicable therapy in patients with persistent corneal epithelial defects. When the drops are applied by trained personnel, the absence of contamination can be ensured up to the 4th day. By additional application of prophylactic antibiotic drops, infections may be avoided even if refrigerated non-preserved autologous serum is used up to 7 days.

Changes in the tear film and ocular surface from dry eye syndrome

Dry eye syndrome (DES) refers to a spectrum of ocular surface diseases with diverse and frequently multiple aetiologies. The common feature of the various manifestations of DES is an abnormal tear film. Tear film abnormalities associated with DES are tear deficiency, owing to insufficient supply or excessive loss, and anomalous tear composition. These categorizations are artificial, as in reality both often coexist. DES disrupts the homeostasis of the tear film with its adjacent structures, and adversely affects its ability to perform essential functions such as supporting the ocular surface epithelium and preventing microbial invasion. In addition, whatever the initial trigger, moderate and severe DES is characterized by ocular surface inflammation, which in turn becomes the cause and consequence of cell damage, creating a self-perpetuating cycle of deterioration. Progress has been made in our understanding of the aetiology and pathogenesis of DES, and these advances have encouraged a proliferation of therapeutic options. This article aims to amalgamate prevailing ideas of DES development, and to assist in that, relevant aspects of the structure, function, and production of the tear film are reviewed. Additionally, a synopsis of therapeutic strategies for DES is presented, detailing treatments currently available, and those in development.

The cytokine regulation of SPARC production by rabbit corneal epithelial cells and fibroblasts in vitro

OBJECTIVE

SPARC (osteonectin/BM40) is detected in the corneal stroma during the wound-healing process. To understand the metabolism of SPARC in the cornea, we investigated the effects of cytokines and growth factors on SPARC synthesis by rabbit corneal epithelial cells and fibroblasts.

METHODS

Rabbit corneal epithelial cells or fibroblasts were cultured for 3 days with serum-containing minimal essential medium (MEM), then subcultured for 3 days on serum-free MEM with epidermal growth factor (EGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), or interleukin-1beta (IL-1beta). SPARC concentration in the medium was measured by the ELISA method using anti-SPARC monoclonal antibody.

RESULTS

The concentration of SPARC in the conditioned medium of the epithelial cells depended on either cell numbers or cultivation periods. When EGF was added to the medium, the amount of SPARC in the medium decreased. The addition of IL-1beta, PDGF, or TGF-beta did not affect SPARC synthesis by the epithelial cells. The production of SPARC by rabbit corneal fibroblasts was low compared with that by epithelial cells. However, the synthesis of SPARC by corneal fibroblasts was significantly enhanced by the addition of TGF-beta. The addition of IL-1beta, PDGF, or EGF slightly increased SPARC synthesis by corneal fibroblasts.

CONCLUSIONS

Cytokines and growth factors modulate SPARC synthesis by rabbit corneal epithelial cells and fibroblasts. These results suggest that cytokines and growth factors modulate cell-matrix interaction in corneal wound healing, possibly by regulating SPARC synthesis.

Analysis of contact lens intolerance by exploring neuroanatomic integration of ocular surface defense

This paper reviews the anatomic, neuronal and mechanical factors that affect contact lens wear, and outlines several areas where compromised ocular surface defense arising from dysfunctional neuroanatomic integration might be the source of or a contributor to contact lens intolerance. Suggestions for clinical work-up by analyzing neuroanatomic integration are presented as a logical way to dissect this complex problem.

Understanding dry eye syndrome

It was my great pleasure to have had the opportunity to give the conference address in addition to being honored by the Professor Dohlman Award. I am proud of the progress in the understanding of dry eye that has been made over the past couple of decades. However, the clinical application of the knowledge that has accumulated lies in the future. Thus far no effective medication has ever been developed for the treatment of severe dry eye. Cyclosoporine may become the first eyedrops to be used, and a series of new drugs containing androgens, immunomodulators, secretagogues, P2Y2 receptor agonists, and others may follow. I believe that medication for the treatment of dry eye will be developed in the not to distant future, and I hope that at the 4th conference in a few years time, we will be able to share these new treatments for the management of dry eye patients.

Autologous serum eye drops for the treatment of severe dry eye in patients with chronic graft-versus-host disease

We investigated the efficacy and safety of autologous serum eye drops for the treatment of severe dry eye after allogeneic haematopoietic stem cell transplantation (SCT). A total of 14 patients (four males and 10 females; median age, 31.0 years) with severe dry eye associated with chronic graft-versus-host disease (cGVHD) were enrolled in this study. All patients were refractory to treatment with conventional artificial tears. Autologous serum eye drops, a solution made of 20% autologous serum in sterile saline, were applied 10 times per eye per day. The patients were evaluated every 4 weeks according to visual acuity, corneal sensitivity, vital staining of the ocular surface, tear dynamics, and subjective assessments of symptoms (complaints scores). The median follow-up period was 19.4 months (range: 4-41 months). After 4 weeks of treatment, significant improvement was observed in both complaint scores (from 33.7+/-12.3 to 23.6+/-10.6 points; P<0.01) and fluorescein scores (from 5.8+/-2.0 to 2.4+/-0.9 points; P<0.005). Significant improvements were observed also in rose-bengal staining and tear break-up time. In seven of the 14 patients, the responses were maintained for 6-41 months (median:19.4+/-8.3 months), while six of the other seven patients required treatment with punctal plugs in addition to autologous serum eye drops. One of these other seven patients developed eczema around the eyelids, after which the treatment was discontinued. No serious adverse events were observed. We conclude that autologous serum eye drops are safe and effective for treating severe dry eye associated with cGVHD and that more efficient control of dry eye may be achieved by the combined use of autologous serum eye drops with punctal plugs.

Analysis of rabbit tear proteins by high-pressure liquid chromatography/electrospray ionization mass spectrometry

The aim of this study was to develop a fast and reliable analytical procedure for the display of the protein components of tears that can be used to differentiate the status of the ocular surface. Using this new procedure, we analyzed the tear protein components following a corneal wound in the rabbit. Calibrated 10-microL glass, fire-polished capillary micropipettes were used to collect tears from New Zealand White rabbits prior to and daily for 9 days following a unilateral 6-mm diameter centrally placed anterior keratectomy. Tear proteins were eluted by a reversed-phase high-performance liquid chromatography (RP-HPLC) column and the tear protein profile was monitored by electrospray ionization (ESI) mass spectrometry positive total ion current (TIC) chromatography. Tear proteins were reliably separated into 17 peaks, each of which contained one or a number of protein components. The molecular weight of each protein component was determined by on-line ESI. Major tear protein components, lactoferrin, lysozyme (minimally detectable in rabbit tears), albumin, lipocalin, lipophilin and beta2-microglobulin, were tentatively identified by this method. Based on the mass spectrometric data, beta2-microglobulin was found to be glycosylated with N-acetylhexosamine. ESI-positive TIC chromatograms and mass spectra revealed comparative differences in the tear protein spectra after corneal wounding. One day after wounding, rabbit lysozyme with a molecular weight of 14,717 Da was found to be 8-fold higher in the tears of wounded eyes when compared with tears from unwounded eyes. It dropped back to normal 3 days after wounding. The expression of an unidentified tear protein with the molecular weight of 16,060 Da was also elevated after corneal wounding and returned to normal level by day 5. In this study, LC/ESI-MS was developed as a fast, reproducible and simple method for the identification and analysis of many of the protein components of the tears. Importantly, this technique also allows quantification of each component resolved in the chromatogram. This method is very suitable for mapping peptides and proteins (<80 kDa) in tears.

Regulatory pathways in lacrimal gland epithelium

Tears are a complex fluid that continuously cover the exposed surface of the eye, namely the cornea and conjunctiva. Tears are secreted in response to the multitude of environmental stresses that can harm the ocular surface such as cold, mechanical stimulation, physical injury, noxious chemicals, as well as infections from various organisms. Tears also provide nutrients and remove waste from cells of the ocular surface. Because of the varied function of tears, tears are complex and are secreted by several different tissues. Tear secretion is under tight neural control allowing tears to respond rapidly to changing environmental conditions. The lacrimal gland is the main contributor to the aqueous portion of the tear film and the regulation of secretion from this gland has been well studied. Despite multiple redundencies in pathways to stimulate secretion from the lacrimal gland, defects can occur resulting in dry eye syndromes. These diseases can have deleterious effects on vision. In this review, we summarize the latest information regarding the regulatory pathways, which control secretion from the lacrimal gland, and their roles in the pathogenesis of dry eye syndromes.

Treatment of recurrent corneal erosions using autologous serum

PURPOSE

To study the effect of autologous serum in the treatment of recurrent corneal erosions.

METHODS

Eleven eyes of 11 consecutive patients with acute macroform corneal erosions who had suffered several relapses despite receiving different types of treatment were analyzed from November 2000 to February 2002. All patients were treated with autologous serum for 3 months.

RESULTS

Mean follow-up time was 9.4 +/- 3.7 months (range, 4-16). No side effects were noted in any of the treated patients. Treatments prior to the use of autologous serum had failed to avoid recurrences in all the patients, with the mean recurrence rate being 2.2 recurrences per month of follow-up. After the onset of serum treatment, only a single recurrence was recorded in three of the patients (0.028 recurrences per month of follow-up).

CONCLUSION

The use of autologous serum for the treatment of patients with recurrent corneal erosion is effective and safe in reducing the number of recurrences experienced by patients.

Controlled study of the use of autologous serum in dry eye patients

PURPOSE

To determine the efficacy and safety of topical autologous serum as a treatment of dry eye patients.

METHODS

A 2-month, prospective, single-masked, placebo-controlled study was conducted in patients with bilateral severe dry eye. One eye was randomized to receive the patient's own serum as a tear substitute, and the fellow eye received unpreserved normal saline solution as a placebo. Subjective symptoms and clinical parameters of dry eye including conjunctival impression cytology were assessed at baseline and 1 week, 1 month, and 2 months after treatment.

RESULTS

Twelve dry eye patients were enrolled. Both subjective symptoms (discomfort, foreign-body sensation, dryness, and photophobia), objective signs (fluorescein and rose bengal staining and conjunctival impression cytology) improved significantly in treated eyes compared with baseline. Control eyes also had improvement in symptoms, signs, and rose bengal staining compared with baseline. Neither Schirmer test results nor tear break-up time improved in either group. The means score of all parameters were improved in both groups, and the results of conjunctival impression cytology were better in treated eyes; however, these results are not significantly different. There were no serious adverse effects observed in this study.

CONCLUSIONS

There was a trend toward improvement in symptoms and signs of dry eye including cytologic changes after application of autologous serum in severe dry eye patients. However, this trend was not statistically significant. A larger scale study is warranted.

Characteristics of the human ocular surface epithelium

An appreciation of the biological characteristics of the human ocular surface epithelium affords us a great insight into the physiology of the human ocular surface in health and disease. Here, we review five important aspects of the human ocular surface epithelium. First, we recognize the discovery of corneal epithelial stem cells, and note how the palisades of Vogt have been suggested as a clinical marker of their presence. Second, we introduce the concept of the gene expression profile of the ocular surface epithelium as arrived at using a new strategy for the systematic analysis of active genes. We also provide a summary of several genes abundantly or uniquely expressed in the human corneal epithelium, namely clusterin, keratin 3, keratin 12, aldehyde dehydrogenase 3 (ALDH3), troponin-I fast-twitch isoform, ssig-h3, cathepsin L2 (cathepsin V), uroplakin Ib, and Ca(2+)-activated chloride channel. Genes related to limbal and conjunctival epithelia are also described. Third, we touch upon the genetic abnormalities thought to be involved with epithelial dysfunction in Meesmann's dystrophy, gelatinous drop-like corneal dystrophy, and the ssig-h3-mutated corneal dystrophies. Fourth, we provide an update regarding the current state of knowledge of the role of cytokines, growth factors and apoptosis in relation to ocular surface homeostasis and tissue reconstruction; the main factors being epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), transforming growth factor-ss (TGF-ss), and some inflammatory cytokines. Fifth, corneal epithelial barrier function and dysfunction as measured by fluorophotometry is remarked upon, with an explanation of the FL-500 fluorophotometer and its ability to detect corneal epithelial dysfunction at a subclinical level. The research described in this review has undoubtedly generated a complete understanding of corneal epithelial pathophysiology-an understanding that, directly or indirectly, has helped advance the development of new therapeutic modalities for ocular surface reconstruction.

Human tear fluid PDGF-BB, TNF-alpha and TGF-beta1 vs corneal haze and regeneration of corneal epithelium and subbasal nerve plexus after PRK

The aim was to determine the association of tear fluid cytokine levels and post-PRK corneal haze evaluated by in vivo confocal microscopy. In addition, the possible association between subbasal neural regeneration and haze formation, or epithelial regeneration were investigated. Twenty eyes of 20 patients (16 women and four men, age 30.7 +/- 7.5 years, range 21-48 years) underwent a myopic PRK. The spherical equivalent (SE) of the intended correction was -4.7 +/- 1.5 D (range -2.75 to -9.00 D). ELISA-methods were used to assess tear fluid concentrations of TGF-beta1, PDGF-BB and TNF-alpha pre-operatively, and post-operatively on day 2 and at 3 months. Tear fluid flow in the collection capillary was recorded, and rates of cytokine release (= tear fluid flow-corrected concentrations) were calculated. In vivo confocal microscopy was performed at 3 months to evaluate the corneal morphology and to determine numerical haze estimate. There was wide interindividual variation between pre-operative and post-operative concentrations and rates of release of TGF-beta1, PDGF-BB and TNF-alpha. Subepithelial haze was observed in all corneas and the mean haze estimate was 506 +/- 401 U (100-1410 U). However, no association was found between tear fluid cytokine levels and post-PRK haze. Regenerating subbasal nerve plexus was found in 18 out of 20 corneas; in two corneas it was absent or could not be visualized due to subepithelial haze. The density of the subbasal nerve fiber bundles had a positive correlation with the epithelial thickness (Pearson correlation, r = 0.56, P = 0.011), but not with the haze estimate or the thickness of the haze area. At 3 months post-PRK, haze could be observed in all patients. The results suggest that tear fluid cytokine analysis, as measured, may not be suitable for screening the potential candidates for haze formation. We did not find any correlation between haze and regeneration of subbasal nerve plexus, but we demonstrated that the regeneration of subbasal nerve plexus might have significant influence on regulation of epithelial healing.

The epidermal growth factor receptor (EGFR): role in corneal wound healing and homeostasis

To evaluate the role of the epidermal growth factor receptor (EGFR) in corneal epithelial wound healing, the effect of an EGFR inhibitor on epithelial cell proliferation and cell stratification during wound healing was investigated. From 3 days prior to wounding until wound healing was complete, rats were systemically treated with either an EGFR tyrosine kinase inhibitor (ZD1839) at 40 mg kg(-1) day(-1)or 80 mg kg(-1) day(-1), or with vehicle only (control). A single corneal wound was made in the center of 66 rat corneas, using a 6.0 mm glass tube wrapped in tissue paper soaked in n-heptanol. Subsequently, each wound was photographed and measured by a computer-assisted digitizer every 12 hr. To determine the number of cells in S phase, entire corneas were labelled with (3)H-thymidine and subjected to autoradiography at 0, 12, 24 and 48 hr after wounding. Epithelial thickness was also measured at these time points by microscopy. Epithelial wound healing was significantly and dose-dependently delayed following administration of ZD1839. At 24 hr after wounding, the number of S-phase cells in the limbal corneal epithelium was significantly lower in both the treated groups compared with the control group (P < 0.05). In the cornea before wounding (0 hr) and at 48 hr post-wounding, epithelial thickness was also significantly less in treated rats compared with controls (P < 0.05). These results indicate that EGFR inhibition affects epithelial cell proliferation and stratification during corneal epithelial wound healing and may play a role in maintaining normal corneal epithelial thickness.

The role of cytokines in corneal immunopathology

Cytokines play an important role in the pathogenesis of various corneal diseases and during corneal graft rejection. Furthermore, cytokines may also play a role in the maintenance of the integrity of the normal cornea. This review focuses on the effects of several cytokines in corneal immunopathology, including the type of the corneal immune response, angiogenesis, chemotaxis, apoptosis, wound healing, corneal disease, and transplantation. It may provide clues for the future treatment of corneal disease and corneal transplantation rejection.

The diagnosis and management of dry eye: a twenty-five-year review

PURPOSE

To review the advances in the diagnosis, pathogenesis, and management of dry eye disease in the past 25 years.

METHODS

Literature review.

RESULTS

The preocular tear film is a hydrated mucus gel that contains soluble antimicrobial proteins and growth factors that protect and support the ocular surface. The final common pathway in dry eye is a perturbation of the integrated ocular surface/lacrimal gland reflex unit. Diagnostic tests evaluating tear composition and clearance appear to show stronger correlation with the severity of ocular irritation symptoms and keratoconjunctivitis sicca (KCS) than the conventional Schirmer tests. KCS is a condition of abnormal differentiation and mucus production by the ocular surface epithelium that results in a poorly lubricated, abnormally permeable ocular surface that has increased susceptibility to environmental insults. Chronic subclinical ocular surface inflammation appears to play a key role in the pathogenesis of KCS. New therapeutic strategies are aimed at reducing the ocular surface inflammation of dry eye disease.

CONCLUSIONS

There has been a tremendous increase in knowledge regarding dry eye disease in the past 25 years that has resulted in improved diagnostic classification and new targeted therapies.

Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses

OBJECTIVE-To characterize healing of corneal epithelial defects in horses and to evaluate the ability of epidermal growth factor (EGF) to modulate rate of corneal epithelial healing in horses.

SAMPLE POPULATION

20 eyes in 12 adult horses.

PROCEDURE

Corneal epithelial wounds were created by mechanically debriding the limbus. Corneal healing was recorded for 3 treatment groups: 50 microg of EGF/ml (n = 5 eyes), 5 microg of EGF/ml (7), and PBS solution (8). Corneal healing was recorded once daily after instillation of fluorescein stain by use of photography and calculating the area of the wound, using imaging software.

RESULTS

After corneal debridement, re-epithelialization was rapid and progressed in a linear fashion for the first 5 to 7 days after surgery in all groups. After that period, rates of healing decreased. A profound increase in the degree of inflammation, neovascularization, melanosis, and scarring was observed in eyes treated with the high dose of EGF (50 microg/ml), but there was not a statistical difference in mean healing time or in mean decrease in radius during the linear phase between the control and either EGF treatment groups. However, for all 8 horses in which both eyes were debrided, the first eye healed significantly faster than the second eye, regardless of treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Beneficial effects of topical administration of a high dose of EGF for acceleration of healing of corneal defects in eyes of horses are outweighed by the intensity of the associated inflammatory response.

Distribution of growth factors and immune cells are altered in the lacrimal gland during pregnancy and lactation

We have undertaken a series of studies to elucidate the roles of growth factors (FGF-2, EGF, TGF-beta1) and prolactin (PRL) in lacrimal gland function during pregnancy and lactation, and to better understand the status of the immune system within the lacrimal gland during those physiological states. In this initial study, lacrimal glands of pregnant (d15, d29), lactating (9d, 22d), and adult female control rabbits, were evaluated by immunohistochemistry, Western blotting and image analysis. In control rabbits EGF, TGF-beta1, and PRL, were immunolocalized primarily in the apical cytoplasm of intralobular ductal epithelial cells, and acini demonstrated a basement membrane-associated immunopositivity for TGF-beta1. FGF-2 immunolocalized in myoepithelial cells in the basal ductal epithelium and complexed to the basement membrane enclosing ducts and acini. Cells immunopositive for immune cell markers (RTLA and CD18) were apparent primarily around interlobular ducts. In d29 pregnant rabbits immunopositivity for EGF and TGF-beta1 was increased within intralobular ducts, both apically and basally, and within some interlobular ductal epithelial cells. Immunopositivity for PRL was strongest in d29 pregnant rabbits within the apical and basal cytoplasm of intralobular ductal epithelial cells. Immunopositivity for FGF-2 in myoepithelial cells was strong in d15 and d29 pregnant rabbits, although basement membrane-associated immunopositivity around acini was often decreased. Immunostaining for EGF and TGF-beta1 in lactating rabbits was similar to that in d29 pregnant rabbits, although basement membrane-associated immunopositivity around acini was more comparable to controls. By 22d lactation immunopositivity for FGF-2 closely resembled that in controls. Image analysis of pregnant and lactating rabbits demonstrated that cells immunopositive for RTLA and CD18 were less abundant around ducts and more abundant between acini, although in 22d lactating rabbits the size of periductal foci was increased to nearly that of controls. Western blots correlated well with the immunohistochemistry. Our findings demonstrate that pregnancy and lactation are accompanied by a shift in the distributions of growth factors and PRL, suggestive of increased release both apically into the lacrimal fluid and basally into the interstitium. Additional shifts in the distributions of cells of the immune system from periductal foci to interacinar sites suggest that there is a recruitment of immune cells away from ducts and toward the connective tissue interstitium surrounding the acini, possibly as part of a heightened state of immune readiness during pregnancy and lactation.

Detection of human herpesvirus 6 and varicella-zoster virus in tear fluid of patients with Bell's palsy by PCR

Human herpesvirus 6 DNA was detected by PCR in the tear fluid of 7 (35%) of 20 patients with Bell's palsy and of 1 (5%) of 20 healthy controls. Varicella-zoster virus was detected by PCR in the tear fluid of 2 of 20 Bell's palsy patients but in none of the tear fluids from 20 healthy controls. These findings suggest an association between human herpesviruses and Bell's palsy.

Corneal insult affects the production and distribution of FGF-2 within the lacrimal gland

The purpose of this study was to determine the distribution of FGF-2 within rabbit lacrimal glands and to determine whether corneal insult affects that distribution. The scarified corneas of experimental animals were inoculated either with adenovirus type 5 or buffer. Control animals were either untreated, or animals whose corneas were scarified. Twenty-one days later all animals were killed and the lacrimal glands were studied by immunocytochemistry and Western blotting to detect FGF-2. In untreated control animals, FGF-2 was immunolocalized predominantly within a population of elongated cells in the basal epithelium of ducts, and to a lesser degree in the basal epithelium of the acini. The elongated immunopositive cells appear to be myoepithelial cells known to be present at these sites. Interstitial cells around ducts and acini, and the basement membranes of the ducts and acini, were also immunopositive for FGF-2. Twenty-one days after adenovirus inoculation and scarification of the cornea, immunopositivity for FGF-2 was dramatically decreased in basement membranes, but increased within myoepithelial cells of the duct epithelium. These myoepithelial cells were frequently enlarged, bulging toward the duct lumen. In animals whose corneas were inoculated with buffer and scarified, or animals whose corneas were simply scarified, the changes in the lacrimal gland were similar, but somewhat less pronounced, to those of adenovirus-inoculated animals. Western blots confirmed the presence of FGF-2 immunoreactivity in all groups. The major band in untreated controls was at 24 kD, whereas all animals with corneal scarification had major bands at 38 kD. Densitometry of Western blots demonstrated that the amount of 24 kD FGF-2 present within the lacrimal gland after corneal scarification was at least 50% less than in untreated controls, whereas 38 kD FGF-2 was at least ten-fold greater. Our findings indicate that corneal scarification results in an altered distribution of FGF-2 within the lacrimal gland, which involves a decrease in low molecular weight FGF-2 and a dramatic increase in a higher molecular weight isoform of FGF-2. FGF-2 may be released from myoepithelial cells apically (exocrine) into the tear fluid and basally (autocrine/paracrine) into the connective tissue, as well as from extracellular complexes within basal laminae.