Epidermal growth factor (EGF) in ocular fluids: presence, origin and therapeutical considerations

Topical Umbilical Cord Serum for Corneal Epithelial Defects after Diabetic Vitrectomy

PURPOSE

To evaluate the role of topical umbilical cord serum (TUCS) therapy in treating corneal epithelial defects (CEDs) after diabetic vitrectomy.

METHODS

In this double-masked, randomized clinical trial, we included 80 eyes of 80 patients who were candidates for vitrectomy due to proliferative diabetic retinopathy complications. In cases of corneal edema obscuring the fundus view during surgery, the corneal epithelium was removed using a 6-mm trephine and a blade no.15. The day after the surgery, patients were randomly divided into two groups: (1) the TUCS group that received 20% TUCS six times/day in addition to the conventional treatment of CED and (2) the control group, which was prescribed artificial tears as placebo in addition to the conventional treatment of CED. The rate of healing of CEDs was measured via two maximum linear dimensions perpendicular to each other at the start of therapy and on postoperative days 1-5, 7, and 12.

RESULTS

Of 80 eyes, 40 were assigned to each treatment group. The mean times to complete CED healing were 2.4 ± 0.7 and 3.8 ± 2.1 days in the TUCS and control groups, respectively (P < 0.001). Persistent CED occurred in two eyes in the control group but in no eyes in the TUCS group.

CONCLUSION

TUCS therapy may be safe and effective in healing CEDs after vitrectomy in patients with diabetes.

Age- and sex-associated changes in prosaposin and its receptors in the lacrimal glands of rats

Prosaposin, a saposin precursor, is a potent neurotrophic factor found in several tissues and various biological fluids. Saposin-deficient patients have different ophthalmic disorders, indicating a relationship between ocular health and prosaposin. However, there is little information about prosaposin on the ocular surface. Because ocular functions are diverse and depend on age and sex, we examined whether prosaposin and its receptors, G protein-coupled receptor 37 (GPR37) and GPR37L1, are expressed in the major ocular glands, the extra orbital lacrimal gland (ELG), and harderian gland (HG) of rats and whether sex and aging affect their expression. Immunohistochemical analyses revealed that prosaposin and its receptors were expressed in the ELGs and HGs of rats, although their expression varied based on the type of gland, age, and sex. Prosaposin, GPR37, and GPR37L1 were expressed in the basolateral membranes and cytoplasm of acinar cells of the ELGs, and their immunoreactivities were higher in female rats of menopausal age than age-matched male rats. However, such age- and sex-related differences in the immunoreactivities of prosaposin, GPR37, and GPR37L1 were not observed in the HGs. Triple immunofluorescence labelling revealed that prosaposin, GPR37, and GPR37L1 were co-localised in the acinar and ductal cells in the ELGs, although the degrees of colocalization varied according to the age and sex of the rats. Together, the present results showed that prosaposin and its receptors were expressed in the major ocular glands of rats, and their immunoreactivities to the ELGs differed considerably with age and sex.

[A method of treating purulent corneal ulcer in the eyes with neuroparalytical keratitis and lagophthalmos]

PURPOSE

To develop a method for treatment of advanced purulent corneal ulcers in eyes with neurotrophic keratitis that developed as a complication of intracranial pathological processes or brain surgeries.

MATERIAL AND METHODS

The study involved 13 patients (14 eyes) that underwent combined surgery - keratoplasty, autoconjunctival flap covering, partial tarsorrhaphy performed simultaneously. Before and after the surgery, patients received frequent instillations of antimicrobial agents and autologous serum.

RESULTS

The organ of vision was preserved in all patients, visual function - in 50% of cases, it improved in 35.7% of cases from 0.07±0.05 to 0.26±0.11. Lagophthalmos has decreased from 6.11±0.99 to 2.78±0.62 mm.

CONCLUSION

Patients with intracranial lesions and complicated by neurotrophic keratitis and lagophthalmos often develop advanced severe and progressive corneal purulent ulcers, which seldom respond to the most active conservative therapy. Simultaneous surgery that includes keratoplasty, auto conjunctival flap covering and partial superficial tarsorrhaphy is an effective treatment option that helps preserve visual function in such eyes.

Reflections on Dry Eye Syndrome Treatment: Therapeutic Role of Blood Products

Dry eye syndrome (DES) is a multifactorial, frequent, pathology characterized by deficient tear production or increased evaporation of tears and associated with ocular surface alteration and inflammation. It mostly affects, but not exclusively, older individuals and leads to varying degrees of discomfort and decreased quality of life. Although the typical treatments of DES rely on using artificial tears, polyunsaturated fatty acids, integrin antagonists, anti-inflammatory agents, or on performing punctal occlusion, recently, standardized blood-derived serum eye drops (SED) are generating much interest as a new physiological treatment option. The scientific rationale in using SED for treating or releasing the symptoms of DES is thought to lie in its composition in multiple factors that resembles that of tears and contributes to the healing and protection of the ocular surface. This manuscript seeks to provide relevant background information on the management of DES, and on the increasing role that various types of SED or platelet lysates, from autologous or allogeneic origins, are playing in the improved therapeutic management of this pathology. The increasing role played by blood establishments in producing better-standardized SED is also addressed.

Solvent/Detergent Virally Inactivated Serum Eye Drops Restore Healthy Ocular Epithelium in a Rabbit Model of Dry-Eye Syndrome

Application of autologous serum eye drops (SEDs) is a recognized means to treat severe dry-eye syndrome (DES). Due to the inconvenience and difficulty of preparing SEDs from some patients, producing SEDs from allogeneic blood donations is gaining popularity. A major safety concern associated with allogeneic blood is virus transmission. We therefore herein evaluated the possibility of applying a solvent/detergent (S/D) treatment to inactivate viruses and studied the impacts of such treatment of SEDs to resolve DES in a rabbit model. Sera prepared from the blood of five rabbits were pooled and divided into two sub-pools. One was untreated (SEDs), while the other was virally-inactivated with 1% Tri-n-butyl phosphate/1% Triton X-45 at 31°C for 1 h (S/D-SEDs). DES was induced in rabbits using 0.1% benzalkonium chloride (BAC). Rabbits were divided into five groups of two rabbits each. One group was untreated (control), three were treated twice daily for 3 weeks using PBS, SEDs, or S/D-SEDs, and the last received an additional 0.1% BAC (as the negative control). The DES condition was determined by measuring aqueous tear secretion (Schirmer’s test), corneal fluorescein staining, a corneal histologic examination, TUNEL stain apoptosis, and corneal inflammatory marker (tumor necrosis factor-α, interleukin (IL)-1β, IL-8, and IL-6) expressions. We first confirmed that SEDs and S/D-SEDs had similar protein profiles and transforming growth factor (TGF)-β contents. Animal experiments showed that tear secretion did not significantly differ between the SED and S/D-SED groups but was significantly higher than in the PBS group. Eye fluorescein staining revealed dramatic improvements in epithelial defects in groups treated with SEDs or S/D-SEDs, and hematoxylin/eosin staining revealed microscopic epithelial layers similar to those of the untreated controls. Inflammatory markers and TUNEL studies showed that healthy epithelium had been restored in groups treated with SEDs or S/D-SEDs. In conclusion, this preclinical study supports the possibility of using S/D virally inactivated SEDs to treat DES and restore a normal epithelium.

Targeting growth factor supply in keratopathy treatment: comparison between maternal peripheral blood and cord blood as sources for the preparation of topical eye drops

BACKGROUND

Epitheliotrophic growth factors (GF) can be supplied topically to patients with severe keratopathy through a variety of blood-derived products. We compared GF content in adult peripheral blood serum (PB-S) and cord blood serum (CB-S) as potential sources of GF. To limit inter-individual variability the assessment was performed in maternal-child pairs at the time of delivery.

MATERIAL AND METHODS

The amounts of epidermal GF (EGF), insulin-like GF (IGF), transforming GF-beta (TGF-β), vascular endothelial GF (VEGF) in CB units collected from the umbilical vein and PB from mothers (each group n=30) were estimated by enzyme-linked immunosorbent assays. Obstetric characteristics and haematological data were recorded from the archives of the Emilia Romagna Cord Blood Bank. Statistical evaluations were performed by Wilcoxon's test and correlations between variables were determined using Spearman's (ρ) coefficient; p-values <0.05 were considered statistically significant.

RESULTS

EGF, TGF-β and VEGF levels were significantly higher in CB-S than in PB-S (median 1,254.4 vs 646.0 pg/mL, 51.3 vs 38.4 μg/mL and 686.8 vs 30 pg/mL, respectively; all p<0.0001) whereas IGF content was significantly higher in PB-S than in CB-S (159.9 vs 53.5 pg/mL, respectively; p<0.0001). In CB-S, the CD34(+) cell concentration appeared to be related to EGF, IGF and TGF-β levels whereas white blood cell count appeared to be related to EGF and TGF-β levels. VEGF levels showed no relation to the haematological parameters considered. Platelet counts were not related to GF level in either CB or PB.

DISCUSSION

The GF content in the two blood sources was different, with CB containing larger amounts. Each GF selectively regulates cellular processes involved in corneal healing, so the use of PB or CB should be targeted to supply specific GF on the basis of the type and severity of the keratopathy.

Umbilical cord blood serum therapy for the management of persistent corneal epithelial defects

AIM

To evaluate the role of umbilical cord blood serum (CBS) therapy in cases with persistent corneal epithelial defects (PED).

METHODS

Sixteen eyes of 14 patients with PED who were resistant to conventional treatment were treated with 20% umbilical cord serum eye drops. Patients were followed-up weekly until epithelization was complete. The collected data included the grade of corneal lesion (Grade I: epithelial defect+superficial vascularization, Grade II: epithelial defect+stromal edema, Grade III: corneal ulcer+stromal melting), the size of epithelial defect (pretreatment, 7(th), 14(th) and 21(st) days of treatment), and follow-up time was evaluated retrospectively.

RESULTS

The mean size of epithelial defect on two perpendicular axes was 5.2×4.6-mm(2) (range: 2.5-8×2.2-9 mm(2)). Mean duration of treatment was 8.3±5wk. CBS therapy was effective in 12 eyes (75%) and ineffective in 4 eyes (25%). The epithelial defects in 4 ineffective eyes were healed with amniotic membrane transplantation and tarsorrhaphy. The rate of complete healing was 12.5% by 7d, 25% by 14d, and 75% by 21d. The healing time was prolonged in Grade III eyes in comparison to eyes in Grade I or Grade II.

CONCLUSION

The results of the current study indicated the safety effectiveness of CBS drops in the management of PED. The grade of disease seems have a role on the healing time.

ERK/p44p42 mitogen-activated protein kinase mediates EGF-stimulated proliferation of conjunctival goblet cells in culture

PURPOSE

To determine whether activation of the ERK pathway by EGF leads to rat and human goblet cell proliferation.

METHODS

The conjunctiva was removed from male Sprague-Dawley rats. Human conjunctiva was removed during ocular surgery. The tissue was minced and goblet cells were grown. The cells were stimulated with EGF (10(-7) M) for 1 and 5 minutes and Western blot analysis was performed with an antibody against phosphorylated EGFR, to measure the activation of the EGF receptor (EGFR). The cells were incubated with EGF (10(-7) M) for 24 hours, and cell proliferation was measured by WST-8. Inhibitors were added either 20 minutes before EGF or 2 hours after. The cells were stimulated with EGF (10(-7) M) for 1 minute to 24 hours. The number of cells expressing phosphorylated ERK (pERK) in the nucleus and Ki-67 was determined by immunofluorescence.

RESULTS

EGF increased the activation of EGFR in rat conjunctival goblet cells. EGF-stimulated proliferation was inhibited by the EGFR inhibitor AG1478 and the MEK inhibitor U0126 in rat and human cultured goblet cells. EGF caused the translocation of pERK to the nucleus in a biphasic manner. Inhibition of the second peak with U0126 prevented proliferation. EGF-stimulated goblet cells progressed through the cell cycle expressing pERK in the nucleus.

CONCLUSIONS

EGF stimulated human and rat conjunctival goblet cell proliferation by activating the EGFR. EGFR stimulated ERK causing its biphasic translocation to the nucleus. The second peak response is responsible for cell proliferation, but the role of the first peak is not known.

Ascorbate Prophylaxis for Corneal Haze After Photorefractive Keratectomy

PURPOSE

To evaluate whether prophylactic systemic ascorbic acid influences the average level of haze and the incidence of late onset corneal haze after photorefractive keratectomy (PRK).

METHODS

Two consecutive groups of eyes treated with PRK for myopia with or without astigmatism were retrospectively compared. The patients had been treated similarly, with the exception that systemic ascorbate had been supplied orally in one of the groups. Haze intensity was quantified on a scale from 0 (clear cornea) to 4 (anterior chamber not visible). The diagnostic criterion for late onset corneal haze was a haze grade 2 or higher, occurring 4 to 12 months after surgery.

RESULTS

One week, 1, 3, 6, and 12 months after surgery, the group without ascorbate (314 eyes) showed haze of average levels 0.61, 0.51, 0.50, 0.32, 0.10, respectively, and the group with ascorbate (201 eyes) showed haze of average levels 0.38, 0.18, 0.16, 0.09, 0.06, respectively. Comparison of the respective values showed a statistically significant difference between the two groups (P<.01) at 1 week, 1, 3, and 6 months. Late onset corneal haze was observed in 11 eyes in the group without ascorbate, and none was observed in the group with ascorbate (P<.02).

CONCLUSION

This retrospective nonrandomized clinical study suggests that oral ascorbic acid supplementation may have a prophylactic effect against haze development after PRK. However, routine prophylactic use of ascorbate can be recommended only after a randomized, prospective clinical trial substantiates its efficacy.

Treatment of dry eye by autologous serum application in Sjögren's syndrome

AIM

To evaluate the efficacy of autologous serum application for the treatment of dry eye in Sjögren's syndrome.

METHODS

The stability of essential components (EGF, vitamin A, and TGF-beta) in preserved serum were examined following preservation at 4 degrees C and -20 degrees C. In a primary clinical trial, 12 patients with Sjögren's syndrome were treated with autologous serum (diluted to 20% with sterile saline) for 4 weeks, and vital staining of the ocular surface was compared before and after treatment. The effects of serum on mucin (MUC-1) expression were observed in cultured conjunctival epithelial cells in vitro.

RESULTS

EGF, vitamin A, and TGF-beta were well preserved for up to 1 month in the refrigerator at 4 degrees C and up to 3 months in the freezer at -20 degrees C. Rose bengal and fluorescein scores improved significantly from the initial scores of 5.3 and 5.6 to 1.7 and 2.5 after 4 weeks, respectively. The additive effect of human serum for cultured conjunctival epithelial cells showed significant MUC-1 upregulation on the cell surface.

CONCLUSION

Autologous serum application is a safe and efficient way to provide essential components to the ocular surface in the treatment of dry eye associated with Sjögren's syndrome.

Tear EGF concentration following corneal epithelial wound creation

The effect of corneal epithelial wound creation on epidermal growth factor (EGF) concentration in tears was evaluated in order to better understand the effects of EGF on the wound healing process. The tears of New Zealand white rabbits were sampled by micropipette one day prior to wounding, immediately prior to the creation of a 7.5 mm diameter anterior keratectomy wound, immediately following wound creation, and at 1, 2, 3, 7, and 14 days following wounding. A volume of 50 microL was taken at each sampling time, and all tear samples were assayed for EGF by an enzyme linked immunosorbent assay (ELISA). The results demonstrated that the concentration of EGF in the tear layer rises dramatically immediately following wound creation. The basal measured EGF concentration was approximately 600 pg/mL; immediately following wound creation, this rose to approximately 1600 pg/mL. By 1 day following creation of the wound, the concentration of EGF in the tears had returned to the basal level. A second, marginally significant increase in the tear concentration was noted at 3 days post wounding. The EGF concentration in the tears were not significantly different at any other time. The measured dramatic rise in EGF concentration in the tears in response to the creation of a corneal epithelial wound provides further evidence of the importance of tear EGF in the wound healing process. The concentrations in all cases were on the order of ng/mL, suggesting that the intercellular concentrations in this range result in optimal cell stimulation.