Suppression of lipopolysaccharide-induced corneal opacity by hepatocyte growth factor

Keratitis induced by bacterial toxins, including lipopolysaccharide (LPS), is a major cause of corneal opacity and vision loss. Our previous study demonstrates hepatocyte growth factor (HGF) promotes epithelial wound healing following mechanical corneal injury. Here, we investigated whether HGF has the capacity to suppress infectious inflammatory corneal opacity using a new model of LPS-induced keratitis. Keratitis, induced by two intrastromal injections of LPS on day 1 and 4 in C57BL/6 mice, resulted in significant corneal opacity for up to day 10. Following keratitis induction, corneas were topically treated with 0.1% HGF or PBS thrice daily for 5 days. HGF-treated mice showed a significantly smaller area of corneal opacity compared to PBS-treated mice, thus improving corneal transparency. Moreover, HGF treatment resulted in suppression of α-SMA expression, compared to PBS treatment. HGF-treated corneas showed normalized corneal structure and reduced expression of pro-inflammatory cytokine, demonstrating that HGF restores corneal architecture and immune quiescence in corneas with LPS-induced keratitis. These findings offer novel insight into the potential application of HGF-based therapies for the prevention and treatment of infection-induced corneal opacity.

Risk factors for corneal epithelial wound healing: Can sex play a role?

Purpose To determine if sex is associated with corneal epithelial wound healing time in patients with persistent corneal epithelial defects (PCEDs). Methods Retrospective case series on patients with PCED from November 2014 to January 2019. Records of 127 patients with diagnosis of PCED were reviewed. Patients with an epithelial defect that lasted more than two weeks in the absence of an active corneal infection were included. Main outcome was corneal epithelial wound healing time. Results 55 patients (29 males) with a mean age of 65.3 ± 16.5 years were included. No difference was found between female and male patients in terms of risk factors, age, treatment strategies or intervals between visits (median of 15 days in females and 12 days in males; p = 0.24). Median duration of the PCED was 51 days (IQR 32-130), with a median number of 5 clinical visits (IQR 4-8). Female patients had significantly longer healing times (p = 0.004) and a corresponding increase in the number of clinical visits (median of 7 visits vs. 5 clinical visits in males, p = 0.012). Conclusion Results from this study suggest female patients with PCED might have a longer corneal epithelial wound healing duration and may therefore require earlier intervention.

β-blocker eye drops affect ocular surface through β2 adrenoceptor of corneal limbal stem cells

Background Topical application of β-blocker eye drops induces damage to the ocular surface in clinical. However, the mechanism involved remains incompletely understood. The purpose of this study was to investigate the influence and mechanism of β-blocker eye drops on corneal epithelial wound healing. Methods Corneal epithelial wound healing models were constructed by epithelial scraping including in the limbal region and unceasingly received eye drops containing 5 mg/mL β-blocker levobunolol, β1-adrenoceptor (β1AR)-specific antagonist atenolol or β2-adrenoceptor (β2AR)-specific antagonist ICI 118, 551. For the migration assay, the murine corneal epithelial stem/progenitor cells (TKE2) were wounded and subsequently incubated with levobunolol, atenolol, or ICI 118, 551. The proliferation and colony formation abilities of TKE2 cells treated with levobunolol, atenolol, or ICI 118, 551 were investigated by CCK-8 kit and crystal violet staining. The differentiation marker Cytokeratin 3 (CK3), the stem cell markers-Cytokeratin 14 (CK14) and Cytokeratin 19 (CK19), and corneal epithelium regeneration-related signaling including in Ki67 and the phosphorylated epithelial growth factor receptor (pEGFR) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) were assessed by immunofluorescence staining. Results Levobunolol and ICI 118, 551 impaired corneal wound healing, decreased the expressions of CK3, CK14, and CK19 after limbal region scraping in vivo and reduced the migration and proliferation of TKE2 in vitro, whereas atenolol had no significant effect. Moreover, levobunolol and ICI 118, 551 inhibited corneal wound healing by mediating the expression of Ki67, and the phosphorylation of EGFR and ERK1/2 in the limbal and regenerated corneal epithelium. Conclusion β-blocker eye drops impaired corneal wound healing by inhibiting the β2AR of limbal stem cells, which decreased corneal epithelial regeneration-related signaling. Therefore, a selective β1AR antagonist might be a good choice for glaucoma treatment to avoid ocular surface damage.

Impact of Different Oxygen Supply Methods on the Healing of Corneal Epithelial Wound and the Level of Acetylcholine

Purpose. To investigate the impact of different oxygen supply methods on corneal epithelial wound healing and acetylcholine level during wound healing. Methods. We randomly divided 75 rabbits into three groups: A, B, and C, with 25 rabbits in each group. The central corneal epithelium was removed from all eyes of the rabbits using a 5 mm trephine. Group A rabbits were given low flow oxygen (3 L/min; concentration: 33%) for 2 h per day through goggles. Group B rabbits were given low flow oxygen (3 L/min; concentration: 33%) for 2 h per day via oxygen masks for inhalation. Group C rabbits healed naturally. The area of healed corneal epithelium and acetylcholine content in corneal epithelium were determined at 12 h, 24 h, and 36 h after injury. Results. At 12 h, 24 h, and 36 h after injury, the healing area of corneal epithelium in the three groups was in the order group A > group B > group C ( P < 0.05 ). At all timepoints, the acetylcholine level in corneal epithelium was in the order of group A > group B > group C ( P < 0.05 ). In all three groups, the acetylcholine content in corneal epithelium showed the order 12 h > 24 h > 36 h ( P < 0.05 ). There was a correlation between acetylcholine expression and the area of unhealed corneal epithelium, and the correlation coefficients of groups A, B, and C were 0.80, 0.83, and 0.85 respectively. Conclusion. Increasing oxygen concentration through inhalation or via goggles can promote corneal epithelial wound healing, but increasing local oxygen concentration of the eye showed a better effect. Acetylcholine may play an important role in the early process of corneal epithelial wound healing.

Effects of Amniotic Membrane Extract Eye Drops on Persistent Epithelial Defects of the Cornea

Purpose: To evaluate the clinical efficacy of amniotic membrane extract eye drops (AMEEDs) in patients with persistent epithelial defects (PEDs) of the cornea.Methods: Sixteen patients with PEDs refractory to the conventional treatment were further treated with AMEEDs six times a day. Visual acuity, visual analog scale (VAS), esthesiometer score, and areas of the epithelial defects before and after 1 and 2 months of treatment were evaluated. After 2 months, AMEEDs were considered effective if all epithelial defects were healed, partially effective if the epithelial defects decreased in size compared with the baseline, and ineffective if the epithelial defects increased in size and required additional treatment.Results: After 2 months of treatment with AMEEDs, there was a reduction in the area of epithelial defects (5.2 ± 3.1 mm2 vs. 0.1 ± 0.1 mm2, respectively, p = 0.01), as well as a significant improvement in best-corrected visual acuity (0.8 ± 0.5 logarithm of minimal angle of resolution [LogMAR] vs. 0.6 ± 0.3 LogMAR, respectively, p = 0.03), and VAS scores (4.3 ± 1.0 vs. 2.8 ± 0.7, respectively, p = 0.04) compared with the baseline values. Treatment with AMEEDs was effective in 13 (81.3%) patients and partially effective in three (18.8%) patients.Conclusions: AMEEDs could stimulate epithelial wound healing and improve ocular symptoms in patients with refractory PED. Therefore, AMEEDs could be considered an effective treatment option for refractory PEDs.