The prophylactic value of TNF-α inhibitors against retinal cell apoptosis and optic nerve axon loss after corneal surgery or trauma

BACKGROUND AND PURPOSE

Late secondary glaucoma is an often-severe complication after acute events like anterior segment surgery, trauma and infection. TNF-α is a major mediator that is rapidly upregulated, diffusing also to the retina and causes apoptosis of the ganglion cells and degeneration of their optic nerve axons (mediating steps to glaucomatous damage). Anti-TNF-α antibodies are in animals very effective in protecting the retinal cells and the optic nerve-and might therefore be useful prophylactically against secondary glaucoma in future such patients. Here we evaluate (1) toxicity and (2) efficacy of two TNF-α inhibitors (adalimumab and infliximab), in rabbits by subconjunctival administration.

METHODS

For drug toxicity, animals with normal, unburned corneas were injected with adalimumab (0.4, 4, or 40 mg), or infliximab (1, 10, or 100 mg). For drug efficacy, other animals were subjected to alkali burn before such injection, or steroids (for control). The rabbits were evaluated clinically with slit lamp and photography, electroretinography, optical coherence tomography, and intraocular pressure manometry. A sub-set of eyes were stained ex vivo after 3 days for retinal cell apoptosis (TUNEL). In other experiments the optic nerves were evaluated by paraphenylenediamine staining after 50 or 90 days. Loss of retinal cells and optic nerve degeneration were quantified.

RESULTS

Subconjunctival administration of 0.4 mg or 4.0 mg adalimumab were well tolerated, whereas 40.0 mg was toxic to the retina. 1, 10, or 100 mg infliximab were also well tolerated. Analysis of the optic nerve axons after 50 days confirmed the safety of 4.0 mg adalimumab and of 100 mg infliximab. For efficacy, 4.0 mg adalimumab subconjunctivally in 0.08 mL provided practically full protection against retinal cell apoptosis 3 days following alkali burn, and infliximab 100 mg only slightly less. At 90 days following burn injury, control optic nerves showed about 50% axon loss as compared to 8% in the adalimumab treatment group.

CONCLUSIONS

Subconjunctival injection of 4.0 mg adalimumab in rabbits shows no eye toxicity and provides excellent neuroprotection, both short (3 days) and long-term (90 days). Our total. accumulated data from several of our studies, combined with the present paper, suggest that corneal injuries, including surgery, might benefit from routine administration of anti-TNF-α biologics to reduce inflammation and future secondary glaucoma.

Emodin suppresses alkali burn-induced corneal inflammation and neovascularization by the vascular endothelial growth factor receptor 2 signaling pathway

OBJECTIVE

To investigate the effects of emodin on alkali burn-induced corneal inflammation and neovascularization.

METHODS

The ability of emodin to target vascular endothelial growth factor receptor 2 (VEGFR2) was predicted by molecular docking. The effects of emodin on the invasion, migration, and proliferation of human umbilical vein endothelial cells (HUVEC) were determined by cell counting kit-8, Transwell, and tube formation assays. Analysis of apoptosis was performed by flow cytometry. CD31 levels were examined by immunofluorescence. The abundance and phosphorylation state of VEGFR2, protein kinase B (Akt), signal transducer and activator of transcription 3 (STAT3), and P38 were examined by immunoblot analysis. Corneal alkali burn was performed on 40 mice. Animals were divided randomly into two groups, and the alkali-burned eyes were then treated with drops of either 10 μM emodin or phosphate buffered saline (PBS) four times a day. Slit-lamp microscopy was used to evaluate inflammation and corneal neovascularization (CNV) in all eyes on Days 0, 7, 10, and 14. The mice were killed humanely 14 d after the alkali burn, and their corneas were removed and preserved at －80 ℃ until histological study or protein extraction.

RESULTS

Molecular docking confirmed that emodin was able to target VEGFR2. The findings revealed that emodin decreased the invasion, migration, angiogenesis, and proliferation of HUVEC in a dose-dependent manner. In mice, emodin suppressed corneal inflammatory cell infiltration and inhibited the development of corneal neovascularization induced by alkali burn. Compared to those of the PBS-treated group, lower VEGFR2 expression and CD31 levels were found in the emodin-treated group. Emodin dramatically decreased the expression of VEGFR2, p-VEGFR2, p-Akt, p-STAT3, and p-P38 in VEGF-treated HUVEC.

CONCLUSION

This study provides a new avenue for evaluating the molecular mechanisms underlying corneal inflammation and neovascularization. Emodin might be a promising new therapeutic option for corneal alkali burns.

The application of a 4D-printed chitosan-based stem cell carrier for the repair of corneal alkali burns

BACKGROUND

Corneal alkali burns can lead to ulceration, perforation, and even corneal blindness due to epithelial defects and extensive cell necrosis, resulting in poor healing outcomes. Previous studies have found that chitosan-based in situ hydrogel loaded with limbal epithelium stem cells (LESCs) has a certain reparative effect on corneal alkali burns. However, the inconsistent pore sizes of the carriers and low cell loading rates have resulted in suboptimal repair outcomes. In this study, 4D bioprinting technology was used to prepare a chitosan-based thermosensitive gel carrier (4D-CTH) with uniform pore size and adjustable shape to improve the transfer capacity of LESCs.

METHODS

Prepare solutions of chitosan acetate, carboxymethyl chitosan, and β-glycerophosphate sodium at specific concentrations, and mix them in certain proportions to create a pore-size uniform scaffold using 4D bioprinting technology. Extract and culture rat LESCs (rLESCs) in vitro, perform immunofluorescence experiments to observe the positivity rate of deltaNp63 cells for cell identification. Conduct a series of experiments to validate the cell compatibility of 4D-CTH, including CCK-8 assay to assess cell toxicity, scratch assay to evaluate the effect of 4D-CTH on rLESCs migration, and Calcein-AM/PI cell staining experiment to examine the impact of 4D-CTH on rLESCs proliferation and morphology. Establish a severe alkali burn model in rat corneas, transplant rLESCs onto the injured cornea using 4D-CTH, periodically observe corneal opacity and neovascularization using a slit lamp, and evaluate epithelial healing by fluorescein sodium staining. Assess the therapeutic effect 4D-CTH-loaded rLESCs on corneal alkali burn through histological evaluation of corneal tissue paraffin sections stained with hematoxylin and eosin, as well as immunofluorescence staining of frozen sections.

RESULTS

Using the 4D-CTH, rLESCs were transferred to the alkali burn wounds of rats. Compared with the traditional treatment group (chitosan in situ hydrogel encapsulating rLESCs), the 4D-CTH-rLESC group had significantly higher repair efficiency of corneal injury, such as lower corneal opacity score (1.2 ± 0.4472 vs 0.4 ± 0.5477, p < 0.05) and neovascularization score (5.5 ± 1.118 vs 2.6 ± 0.9618, p < 0.01), and significantly higher corneal epithelial wound healing rate (72.09 ± 3.568% vs 86.60 ± 5.004%, p < 0.01).

CONCLUSION

In summary, the corneas of the 4D-CTH-rLESC treatment group were similar to the normal corneas and had a complete corneal structure. These findings suggested that LESCs encapsulated by 4D-CTH significantly accelerated corneal wound healing after alkali burn and can be considered as a rapid and effective method for treating epithelial defects.

Dexamethasone and MicroRNA-204 Inhibit Corneal Neovascularization

INTRODUCTION

This was an in vivo animal study designed to investigate the interaction between dexamethasone (Dex) and microRNA-204 (miR-204) in a mouse alkali burn-induced corneal neovascularization (CNV) model. The function of miR-204 was then investigated in human mammary epithelial cells (HMECs) in vitro.

MATERIALS AND METHODS

The CNV model was induced by corneal alkali burn in BLAB/c mice. The mice were randomly divided into five groups: normal control (Ctrl), alkali burn-induced corneal injury (Alkali), alkali burn + Dex (Dex), alkali burn + negative control (NTC), and alkali burn + miR-204 agomir (miR-204). Subconjunctival injection of NTC, Dex, or miR-204 agomir was conducted at 0, 3, and 6 days, respectively, after alkali burn. The corneas were collected at day 7 after injury, and the CNV area was observed using immunofluorescence staining. The expression of miR-204 was analyzed with quantitative real time (qRT)-PCR. In HMECs, exogenous miR-204 agomir or antagomir was used to strengthen or inhibit the expression of miR-204. Migration assays and tube formation studies were conducted to evaluate the function of miR-204 on HMECs.

RESULTS

At 7 days post-alkali burn, CNV grew aggressively into the cornea. MicroRNA-204 expression was reduced in the Alkali group in contrast with the Ctrl group (P = .003). However, miR-204 was upregulated in the Dex group (vs. alkali group, P = .008). The CNV areas in the NTC and miR-204 groups were 59.30 ± 8.32% and 25.60 ± 2.30%, respectively (P = .002). In vitro, miR-204 agomir showed obvious inhibition on HMEC migration in contrast with NTC (P = .033) and miR-204 antagomir (P = .017). Compared with NTC, miR-204 agomir attenuated tube formation, while miR-204 antagomir accelerated HMEC tube formation (P < .05).

CONCLUSION

The role of Dex in attenuating CNV may be partly attributed to miR-204. MiR-204 may be a potential therapeutic target in alkali burn-induced CNV.

URP20 improves corneal injury caused by alkali burns combined with pathogenic bacterial infection in rats

Corneal alkali burns often occur in industrial production and daily life, combined with infection, and may cause severe eye disease. Oxidative stress and neovascularization (NV) are important factors leading to a poor prognosis. URP20 is an antimicrobial peptide that has been proven to treat bacterial keratitis in rats through antibacterial and anti-NV effects. Therefore, in this study, the protective effect and influence mechanism of URP20 were explored in a rat model of alkali burn together with pathogenic bacteria (Staphylococcus aureus and Escherichia coli) infection. In addition, human umbilical vein endothelial cells (HUVECs) and human corneal epithelial cells (HCECs) were selected to verify the effects of URP20 on vascularization and oxidative stress. The results showed that URP20 treatment could protect corneal tissue, reduce corneal turbidity, and reduce the NV pathological score. Furthermore, URP20 significantly inhibited the expression of the vascularization marker proteins VEGFR2 and CD31. URP20 also reduced the migration ability of HUVECs. In terms of oxidative stress, URP20 significantly upregulated SOD and GSH contents in corneal tissue and HCECs (treated with 200 μM H2O2) and promoted the expression of the antioxidant protein Nrf2/HO-1. At the same time, MDA and ROS levels were also inhibited. In conclusion, URP20 could improve corneal injury combined with bacterial infection in rats caused by alkali burns through antibacterial, anti-NV, and antioxidant activities.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Topical formulations of Aprepitant are safe and effective in relieving pain and inflammation, and drive neural regeneration

PURPOSE

To test long-term ocular toxicity and analgesic/anti-inflammatory efficacy of two novel ocular formulations of neurokinin 1 receptor (NK1R) antagonist Aprepitant.

METHODS

for toxicity studies, two Aprepitant formulations (X and Y) were tested on C57BL/6 N mice. Gold standards were 0.4% Oxybuprocaine, 0.1% Diclofenac, or saline. For efficacy studies, C57BL/6 N mice underwent corneal alkali burn, and then received Aprepitant formulation X, Dexamethasone or saline. Eye-drops were applied 3 times/day for 90 days (toxicity) and 14 days (efficacy). Stromal opacity, corneal epithelial damage, nociception and sensitivity were assessed in vivo. The eye-wiping test and corneal sensitivity were assessed to evaluate analgesic efficacy and nerve function. At the end of the experiments mice were euthanized, and corneas were dissected for immunohistochemistry and RT-PCR analyses.

RESULTS

In normal mice, formulation X was not toxic when topically administered for 90 days. Formulation Y was associated with increased leukocyte infiltration in the cornea (p < 0.001). X1 and X2 formulations significantly reduced corneal pain, as Diclofenac and Oxybuprocaine, but did not reduce corneal sensitivity. Formulation Y, instead, was not analgesic at any time point. In the alkali burn model, X1 and X2 formulation enhanced epithelial damage recovery, and reduced inflammation both at day 7 and 14. Moreover, formulation X showed a stronger analgesic effect when compared to the saline and Dexamethasone groups (p < 0.01). Finally, formulation X1 and X2 restored corneal sensitivity by promoting corneal nerve regeneration.

CONCLUSIONS

Aprepitant X formulation is a promising candidate for the treatment of pain associated with inflammation of the ocular surface.

Disulfiram Ophthalmic Solution Inhibited Macrophage Infiltration by Suppressing Macrophage Pseudopodia Formation in a Rat Corneal Alkali Burn Model

FROUNT is an intracellular protein that promotes pseudopodia formation by binding to the chemokine receptors CCR2 and CCR5 on macrophages. Recently, disulfiram (DSF), a drug treatment for alcoholism, was found to have FROUNT inhibitory activity. In this study, we investigated the effect of DSF eye drops in a rat corneal alkali burn model. After alkali burn, 0.5% DSF eye drops (DSF group) and vehicle eye drops (Vehicle group) were administered twice daily. Immunohistochemical observations and real-time reverse transcription-polymerase chain reaction (RT-PCR) analyses were performed at 6 h and 1, 4, and 7 days after alkali burn. Results showed a significant decrease in macrophage accumulation in the cornea in the DSF group, but no difference in neutrophils. RT-PCR showed decreased expression of macrophage-associated cytokines in the DSF group. Corneal scarring and neovascularization were also suppressed in the DSF group. Low-vacuum scanning electron microscopy imaging showed that macrophage length was significantly shorter in the DSF group, reflecting the reduced extension of pseudopodia. These results suggest that DSF inhibited macrophage infiltration by suppressing macrophage pseudopodia formation.

CXCR3 deletion aggravates corneal neovascularization in a corneal alkali-burn model

Corneal neovascularization can cause devastating consequences including vision impairment and even blindness. Corneal inflammation is a crucial factor for the induction of corneal neovascularization. Current anti-inflammatory approaches are of limited value with poor therapeutic effects. Therefore, there is an urgent need to develop new therapies that specifically modulate inflammatory pathways and inhibit neovascularization in the cornea. The interaction of chemokines and their receptors plays a key role in regulating leukocyte migration during inflammatory response. CXCR3 is essential for mediating the recruitment of activated T cells and microglia/macrophages, but the role of CXCR3 in the initiation and promotion of corneal neovascularization remains unclear. Here, we showed that the expression of CXCL10 and CXCR3 was significantly increased in the cornea after alkali burn. Compared with WT mice, CXCR3-/- mice exhibited significantly increased corneal hemangiogenesis and lymphangiogenesis after alkali burn. In addition, exaggerated leukocyte infiltration and leukostasis, and elevated expression of inflammatory cytokines and angiogenic factor were also found in the corneas of CXCR3-/- mice subjected to alkali burn. With bone marrow (BM) transplantation, we further demonstrated that the deletion of CXCR3 in BM-derived leukocytes plays a key role in the acceleration of alkali burn-induced corneal neovascularization. Taken together, our results suggest that upregulation of CXCR3 does not exhibit its conventional action as a proinflammatory cytokine but instead serves as a self-protective mechanism for the modulation of inflammation and maintenance of corneal avascularity after corneal alkali burn.

Prophylactic Instillation of Hydrogen-Rich Water Decreases Corneal Inflammation and Promotes Wound Healing by Activating Antioxidant Activity in a Rat Alkali Burn Model

Many studies have demonstrated the therapeutic effects of hydrogen in pathological conditions such as inflammation; however, little is known about its prophylactic effects. The purpose of this study is to investigate the prophylactic effects of hydrogen-rich water instillation in a rat corneal alkali burn model. Hydrogen-rich water (hydrogen group) or physiological saline (vehicle group) was instilled continuously to the normal rat cornea for 5 min. At 6 h after instillation, the cornea was exposed to alkali. The area of corneal epithelial defect (CED) was measured every 6 h until 24 h after alkali exposure. In addition, at 6 and 24 h after injury, histological and immunohistochemical observations were made and real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to investigate superoxide dismutase enzyme (SOD)1, SOD2, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) mRNA expression. CED at 12 h and the number of inflammatory infiltrating cells at 6 h after injury were significantly smaller in the hydrogen group than the vehicle group. Furthermore, SOD1 expression was significantly higher in the hydrogen group than the vehicle group at both 6 and 24 h, and the number of PGC-1α-positive cells was significantly larger in the hydrogen group than the vehicle group at 6 h after injury. In this model, prophylactic instillation of hydrogen-rich water suppressed alkali burn-induced inflammation, likely by upregulating expression of antioxidants such as SOD1 and PGC-1α. Hydrogen has not only therapeutic potential but also prophylactic effects that may suppress corneal scarring following injury and promote wound healing.

Topical Losartan and Corticosteroid Additively Inhibit Corneal Stromal Myofibroblast Generation and Scarring Fibrosis After Alkali Burn Injury

Purpose

To evaluate the efficacy of losartan and prednisolone acetate in inhibiting corneal scarring fibrosis after alkali burn injury in rabbits.

Methods

Sixteen New Zealand White rabbits were included. Alkali injuries were produced using 1N sodium hydroxide on a 5-mm diameter Whatman #1 filter paper for 1 minute. Four corneas in each group were treated six times per day for 1 month with 50 µL of (1) 0.8 mg/mL losartan in balanced salt solution (BSS), (2) 1% prednisolone acetate, (3) combined 0.8 mg/mL losartan and 1% prednisolone acetate, or (4) BSS. Area of opacity and total opacity were analyzed in standardized slit-lamp photos with ImageJ. Corneas in both groups were cryofixed in Optimal cutting temperature (OCT) compound at 1 month after surgery, and immunohistochemistry was performed for alpha-smooth muscle actin (α-SMA) and keratocan or transforming growth factor β1 and collagen type IV with ImageJ quantitation.

Results

Combined topical losartan and prednisolone acetate significantly decreased slit-lamp opacity area and intensity, as well as decreased stromal myofibroblast α-SMA area and intensity of staining per section and confined myofibroblasts to only the posterior stroma with repopulation of the anterior and mid-stroma with keratocan-positive keratocytes after 1 month of treatment. Corneal fibroblasts produced collagen type IV not associated with basement membranes, and this production was decreased by topical losartan.

Conclusions

Combined topical losartan and prednisolone acetate decreased myofibroblast-associated fibrosis after corneal alkali burns that produced full-thickness injury, including corneal endothelial damage. Increased dosages and duration of treatment may further decrease scarring fibrosis.

Translational Relevance

Topical losartan and prednisolone acetate decrease myofibroblast-mediated scarring fibrosis after corneal injury.

Pycnogenol a promising remedy for diabetic keratopathy in experimentally induced corneal alkali burns in diabetic rats

AIM

This study aimed to investigate the efficiency of topically applied pycnogenol (PYC) in healing the standardized alkaline corneal ulcer in diabetic and normal rats.

MATERIALS AND METHODS

The corneal alkali-burn injury (CA-I) model was unilaterally developed in Wistar rats by filter paper saturated with 0.01 M of NaOH and touching the eyes for 45 s. Rats were divided into four groups: Normal control (NC), normal PYC (NPYC), diabetic control (DC), and diabetic PYC (DPYC). Both NPYC and DPYC groups were daily treated with PY eye drops three times, whereas NC and DC ones were treated with ordinary saline for six successive days.

RESULTS

The wound healing of corneal epithelial was improved in the NPYC group compared to the NC group. Meanwhile, it was significantly improved (P < 0.05) in the DPYC group than in the DC group. Histological examination revealed that corneal re-epithelialization was more accomplished in the DPYC group than in the DC group. In addition, the inflammatory cells were augmented in the DC group more than those in the DPYC one.

CONCLUSION

The findings obtained revealed the efficiency of PYC for enhancing the corneal re-epithelialization and reducing the inflammatory reaction post alkali burn in rats, and thus it could be beneficially valuable as a treatment for the diabetic keratopathy.

Investigating the Anti-Inflammatory Effects of RCI001 for Treating Ocular Surface Diseases: Insight Into the Mechanism of Action

The ocular surface is continuously exposed to various environmental factors, and innate and adaptive immunity play crucial roles in ocular surface diseases (OSDs). Previously, we have reported that the topical application of RCI001 affords excellent anti-inflammatory and antioxidant effects in dry eye disease and ocular chemical burn models. In this study, we examined the inhibitory effects of RCI001 on the Rac1 and NLRP3 inflammasomes in vitro and in vivo. Following RCI001 application to RAW264.7 and Swiss 3T3 cells, we measured Rac1 activity using a glutathione-S-transferase (GST) pull-down assay and G-protein activation assay kit. In addition, we quantified the expression of inflammatory cytokines (interleukin [IL]-1β, IL-6, and tumor necrosis factor [TNF]-α) in lipopolysaccharide (LPS)-stimulated RAW264.7 cells using ELISA and real-time PCR. In the mouse ocular alkali burn model, RCI001 was administered via eye drops (10 mg/mL, twice daily) for 5 days, and 1% prednisolone acetate (PDE) ophthalmic suspension was used as a positive control. Corneal epithelial integrity (on days 0-5) and histological examinations were performed, and transcript and protein levels of Rac1, NLRP3, caspase-1, and IL-1β were quantified using real-time PCR and western blotting in corneal tissues collected on days 3 and 5. We observed that RCI001 dose-dependently inhibited Rac1 activity and various inflammatory cytokines in LPS-stimulated murine macrophages. Furthermore, RCI001 restored corneal epithelial integrity more rapidly than corticosteroid treatment in chemically injured corneas. Compared to the saline group, activation of Rac1 and the NLRP3 inflammasome/IL-1β axis was suppressed in the RCI001 group, especially during the early phase of the ocular alkali burn model. Topical RCI001 suppressed the expression of activated Rac1 and inflammatory cytokines in vitro and rapidly restored the injured cornea by inhibiting activation of Rac1 and the NLRP inflammasome/IL-1β axis in vivo. Accordingly, RCI001 could be a promising therapeutic agent for treating OSDs.

Study of the Effectiveness of Drug No. 1 on the Model of Alkaline Eye Burn in Rabbits

Studies have shown that 0.05 mL/kg of drug No. 1 as 1:15 dilution with sterile saline solution has anti-inflammatory, wound-healing, and angioprotective effects if instilled in both eyes of rabbits twice a day for 30 days after an alkaline burn. A stimulation of reparative processes in the cornea was observed with the test dose of drug No. 1. This was manifested by accelerating the recovery of defects in the anterior epithelium and stroma, reducing the frequency of formation of deep defects and the severity of inflammatory reaction and vascularization, and inhibiting the formation of turbidity of its lower intensity and area. A tendency to restore laminarity of the stroma was determined by the action of drug No. 1 throughout the observation period. This contributed to a decrease in the degree of vascularization and prevented ulceration and perforation of the cornea. By the end of experiment, a restoration of strong epithelial-stromal relationships in the experimental group, compared to the control group, was observed due to formation of normal architectonics of fibrous components of intercellular substance. A more pronounced proliferative activity, with an increase in the layering of limbal epithelial cells, was noted in the limbal zone of the cornea in the experimental group rabbits compared to the control group.

Topical Effects of N-Acetyl Cysteine and Doxycycline on Inflammatory and Angiogenic Factors in the Rat Model of Alkali-Burned Cornea

The aim of this study was to analyze the single and combined effects of N-acetyl cysteine (NAC) and doxycycline (Dox) on the inflammatory and angiogenic factors in the rat model of alkali-burned cornea. Rats were treated with a single and combined 0.5% NAC and 12.5 μg/mL Dox eye drops and evaluated on days 3, 7, and 28. In the corneas of various groups, the activity of Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) enzymes was assessed. The expression of inflammatory factors (TNF-α, Rel-a, and CXCL-1) and angiogenic factors (VEGF-a, MMP2, and MMP9) was measured using real-time polymerase chain reaction. The antioxidant enzyme activities decreased substantially 3 days after injury with sodium hydroxide (NaOH). NAC and combined NAC+ Dox topical treatments increased the SOD enzyme activity on day 28 (P < 0.05). The expression of TNF-α and Rel-a genes following single and combined treatment of NAC and Dox decreased significantly on days 7 and 28 (P < 0.05). The mRNA level of angiogenic factors and corneal neovascularization (CNV) level declined in NaOH-injured rats treated with Dox (P < 0.05). The topical treatment of Dox could attenuate inflammation and CNV complications. However, NAC treatment may not reduce the expression of angiogenic genes.

The effects of hesperidin on stricture formation in corrosive esophageal burns: an experimental study

AIM/BACKGROUND

Esophageal strictures in children that develop as a result of accidental ingestion of corrosive substances remain an important health problem. The purpose of this study is to determine the effects of Hesperidin, an effective bioflavonoid in the proliferative and exudative phase of inflammation, on the stricture formation in corrosive esophageal burns.

METHODS

Experimental esophageal burns in rats were created using a modified Gehanno and Guedon model with 20% NaOH. Rats were divided into 5 groups. In the Sham group, the distal esophagus was prepared and cannulated according to the model, but no NaOH was administrated. The esophageal burn was created with NaOH in the other groups. The burned groups were divided into two groups as untreated (T¹⁴, T²¹) and treated with 100 mg/kg/day Hesperidin (H¹⁴, H²¹) intraperitoneally, and these groups were divided into two according to their sacrification periods (14 and 21 days). Inflammation, fibrosis, and necrosis were graded by histopathological evaluation in all groups. The efficacy of treatment was evaluated using the weight of rats, stenosis index, and histopathological parameters.

RESULTS

Histopathologic damage scores such as inflammation, necrosis, and fibrosis were lower in the H¹⁴ and H²¹ groups and higher in the T¹⁴ and T²¹ groups. And also stenosis index was found higher in T¹⁴ and T²¹ groups (p < 0.05), while it was similar to the Sham group in H¹⁴ and H²¹ groups. No statistically significant difference was found between the H¹⁴ and H²¹ groups in terms of stenosis index. When weights of the rats at the beginning and end of the experiment were compared, weights of the H¹⁴ and H²¹ groups and the Sham group were similar. There was a significant decrease in the weight of the rats in the T¹⁴ and T²¹ groups (p < 0.001).

CONCLUSIONS

This study is the first to use Hesperidin in preventing esophageal damage in an esophageal caustic burn model. It was shown that Hesperidin was effective in reducing macroscopic and microscopic histopathologic damage in the corrosive esophageal burn model, preventing the stricture formation, and has positive effects on nutrition in rats with an esophageal burn.

Drp1-dependent mitochondrial fission mediates corneal injury induced by alkali burn

Corneal alkali burn, one of the most serious ophthalmic emergencies, is difficult to be cured by conservative treatments. It is well known that oxidative stress, inflammation and neovascularization are the main causes of corneal damage after alkali burn, but its underlying mechanism remains to be elucidated. Here, we reported that the expression and phosphorylation (Ser616) of mitochondrial fission protein Drp1 were up-regulated at day 3 after alkali burn, while mitochondrial fusion protein Mfn2 was down-regulated. The phosphorylation of ERK1/2 in corneas was increased at day 1, 3, 7 and peaked at day 3 after alkali burn. In human corneal epithelial cells (HCE-2), NaOH treatment induced mitochondrial fission, intracellular ROS production and mitochondrial membrane potential disruption, which was prevented by Drp1 inhibitor Mdivi-1. In corneas, Mdivi-1 or knockdown of Drp1 by Lenti-Drp1 shRNA attenuated alkali burn-induced ROS production and phosphorylation of IκBα and p65. In immunofluorescence staining, it was detected that Mdivi-1 also prevented NaOH-induced nuclear translocation of p65 in HCE-2 cells. Moreover, the expression of NADPH oxidase NOX2 and NOX4 in corneas peaked at day 7 after alkali burn. Mdivi-1, Lenti-Drp1 shRNA or the mitochondria-targeted antioxidant mito-TEMPO efficiently alleviated activation of NF-κB, expression of NOX2/4 and inflammatory cytokines including IL-6, IL-1β and TNF-α in corneas after alkali burn. In pharmacological experiments, both Mdivi-1 and NADPH oxidases inhibitor Apocynin protected the corneas against alkali burn-induced neovascularization. Intriguingly, the combined administration of Mdivi-1 and Apocynin had a synergistic inhibitory effect on corneal neovascularization after alkali burn. Taken together, these results indicate that Drp1-dependent mitochondrial fission is involved in alkali burn-induced corneal injury through regulating oxidative stress, inflammatory responses and corneal neovascularization. This might provide a novel therapeutic target for corneal injury after alkali burn in the future.

Ocular chemical burn associated with gel type alcohol-based hand sanitizer: A case report

INTRODUCTION

Alcohol-based hand sanitizers (ABHS) are widely used for hand hygiene due to the coronavirus disease pandemic. However, risk awareness regarding its adverse effects is lacking. We aim to report a case of ocular chemical burn that showed severe clinical presentation associated with ABHS.

PATIENT CONCERNS

A 5-year-old girl presented with severe left eye pain after 62% gel-type ABHS splashed into her eye.

DIAGNOSIS

On slit lamp examination, a near total corneal and conjunctival epithelial defect with limbal pale on the lower half of the cornea was noted. Severe ocular burn by ABHS was prominent with suspected limbal stem cell damage.

INTERVENTIONS

She was hospitalized and was prescribed topical medications including antibiotics, steroid eye drops with preservative-free artificial tears, and oral nonsteroidal anti-inflammatory drugs.

OUTCOMES

Despite intensive medical treatments, the corneal and conjunctival epithelial defects showed no improvement up to the 4th hospital day. After additional instillation of autoserum eye drops to promote epithelial healing, the corneal epithelium barely recovered from the temporal limbus. On the third week of admission, the epithelial defect was completely resolved without corneal opacity, although with minimal symblepharon in the lower fornix.

CONCLUSIONS

Gel-type ABHS can cause severe form of ocular chemical burn such as delayed ocular surface healing. In clinical setting, immediate and thorough rinsing of alcohol-based gel and early intensive treatment are crucial.

Canonical NF-κB signaling maintains corneal epithelial integrity and prevents corneal aging via retinoic acid

Disorders of the transparent cornea affect millions of people worldwide. However, how to maintain and/or regenerate this organ remains unclear. Here, we show that Rela (encoding a canonical NF-κB subunit) ablation in K14+ corneal epithelial stem cells not only disrupts corneal regeneration but also results in age-dependent epithelial deterioration, which triggers aberrant wound-healing processes including stromal remodeling, neovascularization, epithelial metaplasia, and plaque formation at the central cornea. These anomalies are largely recapitulated in normal mice that age naturally. Mechanistically, Rela deletion suppresses expression of Aldh1a1, an enzyme required for retinoic acid synthesis from vitamin A. Retinoic acid administration blocks development of ocular anomalies in Krt14-Cre; Relaf/f mice and naturally aged mice. Moreover, epithelial metaplasia and plaque formation are preventable by inhibition of angiogenesis. This study thus uncovers the major mechanisms governing corneal maintenance, regeneration, and aging and identifies the NF-κB-retinoic acid pathway as a therapeutic target for corneal disorders.

Comparison of therapeutic effects between topical 8-oxo-2'-deoxyguanosine and corticosteroid in ocular alkali burn model

We compared the therapeutic effects of topical 8-oxo-2'-deoxyguanosine (8-oxo-dG) and corticosteroid in a murine ocular alkali burn model. (n = 128) The corneal alkali burn model was established by applying 0.1 N sodium hydroxide (NaOH), followed by treatment with 8-oxo-dG, 0.1% fluorometholone (FML), 1% prednisolone acetate (PDE), or phosphate-buffered saline (PBS) twice daily. One week later, the clinical and histological status of the cornea were assessed. Transcript levels of inflammatory cytokines and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as well as the levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the cornea, were assayed. The 8-oxo-dG and PDE groups showed marked improvements in corneal integrity and clarity when compared with the PBS group (each p < 0.01). The numbers of cells stained for neutrophil elastase and F4/80-positive inflammatory cells were significantly decreased, with levels of interleukin(IL)-1β, IL-6, tumor necrosis factor(TNF)-α, and total ROS/RNS amounts markedly reduced in the 8-oxo-dG, FML, and PDE groups (each p < 0.05). Levels of NADPH oxidase type 2 and 4 were substantially more repressed in the 8-oxo-dG-treated group than in the PDE-treated group (each p < 0.05). Topical 8-oxo-dG showed excellent therapeutic effects that were comparable with those treated with topical PDE in a murine ocular alkali burn model.

Subconjunctival injection of tumor necrosis factor-α pre-stimulated bone marrow-derived mesenchymal stem cells enhances anti-inflammation and anti-fibrosis in ocular alkali burns

PURPOSE

To investigate the therapeutic effect of subconjunctival injection of tumor necrosis factor-α (TNF-α) pre-stimulated bone marrow-derived mesenchymal stem cells (BMMSCs) on ocular alkali burns in a rat model.

METHODS

After applying a 6 mm filter paper soaking in 1 N NaOH on the cornea of rats, the suspension of TNF-α pre-stimulated BMMSCs, BMMSCs and PBS were given subconjunctivally and respectively. Corneal epithelial defect, corneal opacity, inflammation as well as PTGS2 and TSG-6 expression on day 7 and fibrosis on day 14 were compared.

RESULTS

TNF-α pre-stimulated BMMSCs group had a more predominate effect on promoting corneal epithelial repairing, decreasing corneal opacity, reducing inflammatory cells and CD68 + macrophages on day 7 and suppressing fibrosis on day 14 compared to BMMSCs group. Besides, it had significant increased expressions of PTGS2 and TSG-6 in vitro. Pre-treated with Indomethacin revealed a reverse effect on above-mentioned changes.

CONCLUSION

Subconjunctival injection of TNF-α pre-stimulated BMMSCs enhanced anti-inflammatory and anti-fibrotic effect in ocular alkali burns, which was possibly though up regulation of PTGS2 and TSG-6 expression.

The Need for Improved Therapeutic Approaches to Protect the Cornea Against Chemotoxic Injuries

Cornea, a highly specialized transparent tissue, is the major refractive element of the eye. The cornea is highly susceptible to chemotoxic injury through topical exposure to vapors, microparticles, and aqueous drops, as well as through systemically absorbed chemicals that access the cornea via tear film, aqueous humor, and limbal vasculature. Corneal injury activates a carefully orchestrated series of repair processes capable of resolving minor lesions over time, but it often fails to overcome the menace of moderate, severe, and chronic injuries and secondary pathophysiologies that permanently impair vision. The most serious complications of chemical injuries-persistent corneal edema, neovascularization, scarring/haze, limbal stem cell deficiency, and corneal melting-often manifest over months to years, suggesting that a better understanding of endogenous regenerative mechanisms of corneal repair can lead to the development of improved treatments that may attenuate or prevent corneal defects and protect vision.

Efficacy of systemic administration of riboflavin on a rabbit model of corneal alkali burn

Changes in the barrier mechanisms in the eye should determine the rational route for the administration and dosage of each drug in the treatment of traumatic injuries and other pathologies. The aim of this study was to examine the efficacy of intra-arterial delivery of 14C-riboflavin (as an "indicator") and compare it with intravenous and intramuscular administration in an animal model of chemical eye burn. 14C-riboflavin (14C-I) was administered by intra-arterial (carotid artery), intravenous (femoral vein) and intramuscular (femoral muscle) routes. The total radioactivity was determined over 2 h in the plasma and structures of the rabbit's eyes using a scintillation counter. The results of the study show that intravascular administration of 14C-I gives significantly higher concentrations of total radioactivity in the blood and is accompanied by a significant increase in the permeability of the blood-barrier and barrier in eyes suffering from burns. The highest concentration in the plasma and aqueous humour of the anterior chamber of the eye was observed during the first hour with the intra-arterial route of administration of 14C-I in either burnt and unburnt eyes. The distribution of total radioactivity in the structures of the eye over the 2 h of the experiment showed a higher level of the drug under intra-arterial administered in the uveal regions, namely: the iris, ciliary body, choroid, retina and also the sclera and cornea. This experimental model shows that intra-arterial administration can increase the bioavailability of a drug to the structures of the eye within a short period of time.

MG53 Does Not Manifest the Development of Diabetes in db/db Mice

MG53 is a member of the TRIM protein family that is predominantly expressed in striated muscles and participates in cell membrane repair. Controversy exists regarding MG53's role in insulin signaling and manifestation of diabetes. We generated db/db mice with either whole-body ablation or sustained elevation of MG53 in the bloodstream in order to evaluate the physiological function of MG53 in diabetes. To quantify the amount of MG53 protein in circulation, we developed a monoclonal antibody against MG53 with high specificity. Western blot using this antibody revealed lower or no change of serum MG53 levels in db/db mice or patients with diabetes compared with control subjects. Neither whole-body ablation of MG53 nor sustained elevation of MG53 in circulation altered insulin signaling and glucose handling in db/db mice. Instead, mice with ablation of MG53 were more susceptible to streptozotocin-induced dysfunctional handling of glucose compared with the wild-type littermates. Alkaline-induced corneal injury demonstrated delayed healing in db/db mice, which was restored by topical administration of recombinant human (rh)MG53. Daily intravenous administration of rhMG53 in rats at concentrations up to 10 mg/kg did not produce adverse effects on glucose handling. These findings challenge the hypothetical function of MG53 as a causative factor for the development of diabetes. Our data suggest that rhMG53 is a potentially safe and effective biologic to treat diabetic oculopathy in rodents.

Effects of topical application of platelet-rich plasma on esophageal stricture and oxidative stress after caustic burn in rats: Is autologous treatment possible?

BACKGROUND

Caustic esophageal burn is still an important health problem in pediatric surgery. Although there are a number of experimental and clinical studies to increase the recovery of the esophagus and reduce the stenosis rate, there is no consensus on the treatment protocol. Platelet-rich plasma (PRP) is an autologous blood product, which has positive effects on wound healing, reepithelization and scar prevention. The aim of our study was to investigate the effects of PRP on stricture formation and oxidative status after caustic esophageal injury in rats.

METHODS

Twenty-one rats were divided into three groups [Sham operation (n = 8), corrosive esophageal burn with 30% NaOH (n = 6), topical PRP application after corrosive burn (n = 7)]. On the postoperative 21st day, oxidative markers were measured in the serum, and collagen accumulation and stenosis index were measured histopathologically to assess the efficacy of PRP treatment.

RESULTS

Postoperative weight was higher than preoperative weight in Sham and PRP groups, but lower in the Burn group (p < 0.05). No difference was observed between Sham and PRP groups at total antioxidant status and paraoxonase values, but a significant decrease was found in the Burn group. Group PRP had higher total oxidant status and arylesterase levels than Group Burn (p < 0.05). There was no difference in total thiol values between PRP and Sham group. Histopathological scoring for muscularis mucosa damage revealed a significant reduction in Group PRP, compared to Group Burn (p < 0.05). Esophageal wall thickness and SI were reduced, and luminal diameter was increased in Group PRP compared to Group Burn (p < 0.05).

CONCLUSION

For the first time in the literature, these results indicate that topical PRP treatment after the experimental corrosive burn has a positive effect on oxidative stress, mucosal healing and decreased stricture development. PRP may be an alternative at the clinical treatment because it can be used during diagnostic esophagoscopy.

TYPE OF STUDY

Treatment study Level I (randomized controlled trial).

Amniotic Membrane Transplantation in Acute Severe Ocular Chemical Injury: A Randomized Clinical Trial

PURPOSE

To compare the outcomes of conventional medical treatment vs combined medical treatment and amniotic membrane transplantation (AMT) in the management of patients with Roper-Hall grade IV ocular chemical injury.

DESIGN

Randomized, parallel-controlled clinical trial.

METHODS

Setting: Single tertiary referral hospital.

PATIENTS

Sixty eyes of 60 patients with Roper-Hall grade IV ocular chemical injury with a minimum follow-up of 12 months were enrolled in the study.

INTERVENTION

Patients were randomly assigned to 2 groups: Group 1 (30 eyes) received topical preservative-free lubricating gel and drops, chloramphenicol, betamethasone, homatropine, oral vitamin C, and doxycycline; Group 2 (30 eyes) received amniotic membrane transplant (AMT) on the entire ocular surface in addition to the medical treatment provided in Group 1.

OUTCOME MEASURES

The main outcome measure was time to complete corneal epithelialization. Secondary outcome measures were best-corrected visual acuity (BCVA) and neovascularization in the central 5 mm of the cornea.

RESULTS

Mean follow-up time was 20.3 ± 2.5 months (range 13-24 months). Corneal epithelial defects healed within 72.6 ± 30.4 (21-180) days in Group 1 vs 75.8 ± 29.8 (46-170) days in Group 2 (P = .610). Mean BCVA was 2.06 ± 0.67 (0.4-2.6) logMAR vs 2.06 ± 0.57 (1-2.9) logMAR in Groups 1 and 2, respectively (P = .85). Group 1 developed more central corneal neovascularization (22 eyes; 73.3%) compared to Group 2 (16 eyes; 53.3%); however, it was not statistically significant (P = .108).

CONCLUSIONS

In comparison to conventional medical therapy, combined amniotic membrane transplantation and medical therapy does not accelerate corneal epithelialization or affect final visual acuity in severe chemical injuries.

Neprilysin inhibition promotes corneal wound healing

Neprilysin (NEP), an ectoenzyme that modulates inflammation by degrading neuropeptides, was recently identified in the human corneal epithelium. The cornea expresses many NEP substrates, but the function of NEP in homeostatic maintenance and wound healing of the cornea is unknown. We therefore investigated the role of this enzyme under naive and injured conditions using NEP-deficient (NEP-/-) and wild type (WT) control mice. In vivo ocular surface imaging and histological analysis of corneal tissue showed no differences in limbal vasculature or corneal anatomy between naive NEP-/- and WT mice. Histological examination revealed increased corneal innervation in NEP-/- mice. In an alkali burn model of corneal injury, corneal wound healing was significantly accelerated in NEP-/- mice compared to WT controls 3 days after injury. Daily intraperitoneal administration of the NEP inhibitor thiorphan also accelerated corneal wound healing after alkali injury in WT mice. Collectively, our data identify a previously unknown role of NEP in the cornea, in which pharmacologic inhibition of its activity may provide a novel therapeutic option for patients with corneal injury.

Leukotriene Antagonist S 872419 A for Early-Phase Treatment of Chemical Burn in the Rabbit Eye

S 872419 A, a specific receptor antagonist of peptide leukotrienes, was tested in the early-phase treatment of chemically burned eye (0.25 mol/l sodium hydroxide) of the rabbit. The drug was topically applied 5 times a day in a 1% solution, controls were the untreated opposite eye. Gross and microscopic investigations indicated that S 872419 A inhibits the inflammatory response of the chemically burned anterior eye segment. The parameters of healing considered (epithelial regeneration, corneal clouding and swelling, infiltration with polymorphonuclear leukocytes) suggest inhibition of lipoxygenase-mediated reactions in the tissue. PGF2 alpha levels were the same in aqueous humour of treated and untreated eyes. Further experiments with S 872419 A and other nonsteroidal drugs should improve the anti-inflammatory therapy of the chemically burned eye.

Corneal Epithelial Deficiency Induced by the Use of β-Blocker Eye Drops

Two studies were conducted to check the effects of β-blocker eye drops, 2% carteolol (Mikelan®) and 0.5% timolol (Timoptol®), on regeneration of corneal epithelium in rabbit eyes. For the short-term study, epithelial deficiency was artificially induced in the cornea of albino rabbits. One of the β-blocker eye drops or 0.005% benzalkonium chloride was applied in the right eye and physiological saline solution was applied to the left eye four times a day, and wound healing rate was calculated. Two weeks later, images of the surface epithelium were analyzed by scanning electron microscopy and proliferative capacity was studied, using proliferating cell nuclear antigen as a marker. The long-term study was conducted similarly except that the eye drops were applied twice a day and epithelial deficiency was re-induced every two weeks.

In the short-term study, epithelial wound healing rate was slowed in β-blocker groups. Significant differences were detected between the Mikelan® and Timoptol® groups, and the benzalkonium and physiological saline groups. The β-blocker groups had severe epithelial cell desquamation, as well as detachment. In the long-term study, the Mikelan® group had significantly delayed wound healing at first induction, the benzalkonium group showed delay up to the third induction and the Timoptol® group up to the fifth induction. These studies indicate that β-blocker eye drops delay corneal epithelial wound healing and supported the concept that corneal epithelial deficiency occurs clinically after the long-term administration of β-blocker eye drops.

Chemical Burns of the Eye: The Role of Retinal Injury and New Therapeutic Possibilities

PURPOSE

To propose a new treatment paradigm for chemical burns to the eye - in the acute and chronic phases.

METHODS

Recent laboratory and clinical data on the biology and treatment of chemical burns are analyzed.

RESULTS

Corneal blindness from chemical burns can now be successfully treated with a keratoprosthesis, on immediate and intermediate bases. Long term outcomes, however, are hampered by early retinal damage causing glaucoma. New data suggest that rapid diffusion of inflammatory cytokines posteriorly (TNF-α, etc) can severely damage the ganglion cells. Prompt anti-TNF-α treatment is markedly neuroprotective. Long term profound reduction of the intraocular pressure is also vital.

CONCLUSION

A new regimen, in addition to standard treatment, for severe chemical burns is proposed. This involves tumor necrosis factor alpha (TNF-α) inhibition promptly after the accident (primarily for retinal neuroprotection), prophylactic maximal lowering of the intraocular pressure (starting immediately), and keratoprosthesis implantation in a later quiet state.

Chemical burns: Diphoterine untangled

OBJECTIVE

Diphoterine is a hypertonic, amphoteric, polyvalent and chelating decontamination solution used in the treatment of cutaneous and ocular chemical burns. Due to infrequent use by emergency physicians along with the small number of available studies, its debate in the literature as to its efficacy and safety remains inconclusive.

METHODS

A structured literature search was performed in MEDLINE, EMBASE BIOLOGICAL ABSTRACTS and TOXNET to June 2016 for original English-language studies reporting on the safety and effectiveness of Diphoterine. Methodological and reporting quality of pre-clinical animal studies was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool and Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. Clinical studies were assessed using Chambers' criteria.

RESULTS

13 studies (seven in the pre-clinical, five in the clinical setting and one mixed) met the study inclusion criteria. Pre-clinical studies showed a faster resolution of pH and reduced tissue necrosis with Diphoterine. Clinical studies showed reduced tissue necrosis/severity of symptoms, faster pH resolution and a reduction in pain when using Diphoterine. No adverse events were attributable to Diphoterine. Reporting and methodology of the studies was poor or showed a high risk of bias.

CONCLUSIONS

Diphoterine appears to be safe to use and is probably superior to other rinsing solutions. However, immediate decontamination is imperative and if Diphoterine is not available a different rinsing solution should be used. The methodology of the published literature for Diphoterine is generally poor and future publications should use the frameworks given as templates.

Effects of nicotine on corneal wound healing following acute alkali burn

Epidemiological studies have indicated that smoking is a pivotal risk factor for the progression of several chronic diseases. Nicotine, the addictive component of cigarettes, has powerful pathophysiological properties in the body. Although the effects of cigarette smoking on corneal re-epithelialization have been studied, the effects of nicotine on corneal wound healing-related neovascularization and fibrosis have not been fully demonstrated. The aim of this study was to evaluate the effects of chronic administration of nicotine on corneal wound healing following acute insult induced by an alkali burn. BALB/C female mice randomly received either vehicle (2% saccharin) or nicotine (100 or 200 μg/ml in 2% saccharin) in drinking water ad libitum. After 1 week, animals were re-randomized and the experimental group was subjected to a corneal alkali burn, and then nicotine was administered until day 14 after the alkali burn. A corneal alkali burn model was generated by placing a piece of 2 mm-diameter filter paper soaked in 1N NaOH on the right eye. Histopathological analysis and the expression level of the pro-angiogenic genes vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) revealed that chronic nicotine administration enhanced alkali burn-induced corneal neovascularization. Furthermore, the mRNA expression of the pro-fibrogenic factors α-smooth muscle actin (αSMA), transforming growth factor-β (TGF-β), and collagen α1 (Col1) was enhanced in the high-concentration nicotine-treated group compared with the vehicle group after corneal injury. Immunohistochemical analysis also showed that the αSMA-positive area was increased in chronic nicotine-treated mice after corneal alkali burn. An in vitro assay found that expression of the α3, α7, and β1 nicotinic acetylcholine receptor (nAChR) subunits was significantly increased by chemical injury in human corneal fibroblast cells. Moreover, alkali-induced fibrogenic gene expression and proliferation of fibroblast cells were further increased by treatment with nicotine and cotinine. The proliferation of such cells induced by treatment of nicotine and cotinine was reduced by inhibition of the PI3K and PKC pathways using specific inhibitors. In conclusion, chronic administration of nicotine accelerated the angiogenic and fibrogenic healing processes in alkali-burned corneal tissue.

Mechanisms of Retinal Damage after Ocular Alkali Burns

Alkali burns to the eye constitute a leading cause of worldwide blindness. In recent case series, corneal transplantation revealed unexpected damage to the retina and optic nerve in chemically burned eyes. We investigated the physical, biochemical, and immunological components of retinal injury after alkali burn and explored a novel neuroprotective regimen suitable for prompt administration in emergency departments. Thus, in vivo pH, oxygen, and oxidation reduction measurements were performed in the anterior and posterior segment of mouse and rabbit eyes using implantable microsensors. Tissue inflammation was assessed by immunohistochemistry and flow cytometry. The experiments confirmed that the retinal damage is not mediated by direct effect of the alkali, which is effectively buffered by the anterior segment. Rather, pH, oxygen, and oxidation reduction changes were restricted to the cornea and the anterior chamber, where they caused profound uveal inflammation and release of proinflammatory cytokines. The latter rapidly diffuse to the posterior segment, triggering retinal damage. Tumor necrosis factor-α was identified as a key proinflammatory mediator of retinal ganglion cell death. Blockade, by either monoclonal antibody or tumor necrosis factor receptor gene knockout, reduced inflammation and retinal ganglion cell loss. Intraocular pressure elevation was not observed in experimental alkali burns. These findings illuminate the mechanism by which alkali burns cause retinal damage and may have importance in designing therapies for retinal protection.

Experimental Study of the Effects of Nanodispersed Ceria on Wound Repair

We studied the effects of nanodispersed ceria on wound healing in vitro and in vivo. It was found that cerium dioxide stimulated wound healing, which manifested in shrinkage of burn wound area (by 1.5 times) and intensification (by 2.4 times) marginal epithelialization.

Protective effects of ursodeoxycholic acid in experimental corrosive esophagitis injury in rats

Accidental caustic ingestions are serious medical problems especially in childhood. Various treatment modalities are being used for the complications of caustic injuries such as stricture formation. The aim of this study is to establish whether ursodeoxycholic acid (UDCA) has protective effects on experimental corrosive esophagitis in rats. Twenty four Wistar-albino rats, weighing 220-240 g, were used in the study. Experimental animals were divided in three groups randomly: UDCA treatment group (Group T, n:8), control group (Group K, n: 8) and sham group (Group S, n: 8). In group T and S corrosive esophagitis was induced. UDCA (5 mg/kg) was performed to the group T for 10 days orally. All animals were sacrificed at the end of procedures and histopathological changes in esophageal tissue were scored by a single investigator who was blind to the groups. In group T inflammation was present in two rats, muscularis mucosa injury in two rats, grade 1 collagen deposition in six rats and grade 2 in two rats. In comparison with group S these were statistically significant (p value was 0.003, 0.003 and 0.015, respectively). UDCA has protective effect in experimental corrosive esophagitis.

KEY WORDS

Corrosive esophagitis, Rat, Stricture, Ursodeoxycholic acid.

[Use of corticosteroids in esophagitis caustic ingestion. Report of two cases]

Exposure to potentially toxic substances represents 0.3% of annual visits to a pediatric emergency department, being a situation likely to be prevented and that generates a non-negligible morbidity and mortality. The most common route of exposure is the oral and drugs are the products most frequently involved. Esophagitis caustic ingestion of corrosive substances in childhood is now a public health problem in developing countries. Clinical manifestations vary from no injuries serious commitment to high risk of death observed more frequently in patients between one and three years old. In addition to drilling, the most severe complication of esophagitis is caustic stricture formation, which occurs at a frequency of 5% to 47% in severe cases. The role of systemic corticosteroids in preventing caustic esophageal stenosis is still considered controversial, despite the many published reports showing your benefit. We report two cases of pediatric patients with caustic esophagitis IIB Zargar who received systemic corticosteroids with favorable evolution.

[Hydrofluoric acid burns]

Hydrofluoric acid is increasingly used as a rust remover and detergent. Dermal contact with hydrofluoric acid results in a chemical burn characterized by severe pain and deep tissue necrosis. It may cause electrolyte imbalances with lethal consequences. It is important to identify high-risk patients. 'High risk' is defined as a total affected body area > 3% or exposure to hydrofluoric acid in a concentration > 50%. We present the cases of three male patients (26, 31, and 39 years old) with hydrofluoric acid burns of varying severity and describe the subsequent treatments. The application of calcium gluconate 2.5% gel to the skin is the cornerstone of the treatment, reducing pain as well as improving wound healing. Nails should be thoroughly inspected and possibly removed if the nail is involved, to ensure proper healing. In high-risk patients, plasma calcium levels should be evaluated and cardiac monitoring is indicated.

[Selection of decontaminants for experimental phenol burn wounds]

OBJECTIVE

To investigate the effect of the decontaminants frequently used for phenol burn wounds.

METHODS

The central part of the dorsal skin of adult male Sprague-Dawley rats were burned with 90% (W/V)phenol solution for 2 min, and water, 75% ethanol, polyethylene glycol 400 (PEG400), and Diphoterine were applied for decontamination for 15 min. The changes in wounds were observed, and the depth of skin burns at 24 hours after treatment and changes in six indicators of organ injuries, i.e., serum levels of total bilirubin (TBil), creatinine (Crea), alanine aminotransferase (ALT), alanine aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LDH), at 6 hours after treatment were compared.

RESULTS

After phenol burns, the Diphoterine group had a significantly better effect and significantly lower degrees of skin and organ injuries compared with the water group (P<0.05). The effect of decontamination and degrees of skin and organ injuries were similar between the 75% ethanol group and the PEG400 group, and both groups had a better effect of decontamination compared with the water group; the 75% ethanol group had significantly lower serum levels of CK and LDH than the water group (P<0.05). Among these four groups, the water group had the worst effect, the deepest wounds, and the most severe organ injuries.

CONCLUSION

After phenol burns, early decontamination with water has a poor effect, while Diphoterine can reduce the depth of phenol burns and the degrees of injuries of vital organs, and has a good effect of decontamination.

Development of a novel in vivo corneal fibrosis model in the dog

The aim of this study was to develop a novel in vivo corneal model of fibrosis in dogs utilizing alkali burn and determine the ability of suberanilohydroxamic acid (SAHA) to inhibit corneal fibrosis using this large animal model. To accomplish this, we used seven research Beagle dogs. An axial corneal alkali burn in dogs was created using 1 N NaOH topically. Six dogs were randomly and equally assigned into 2 groups: A) vehicle (DMSO, 2 μL/mL); B) anti-fibrotic treatment (50 μM SAHA). The degree of corneal opacity, ocular health, and anti-fibrotic effects of SAHA were determined utilizing the Fantes grading scale, modified McDonald-Shadduck (mMS) scoring system, optical coherence tomography (OCT), corneal histopathology, immunohistochemistry (IHC), and transmission electron microscopy (TEM). The used alkali burn dose to produce corneal fibrosis was well tolerated as no significant difference in mMS scores between control and treatment groups (p = 0.89) were detected. The corneas of alkali burned dogs showed significantly greater levels of α-smooth muscle actin, the fibrotic marker, than the controls (p = 0.018). Total corneal thickness of all dogs post-burn was significantly greater than baseline OCT images irrespective of treatment (p = 0.004); TEM showed that alkali burned corneas had significantly greater minimum and maximum interfibrillar distances than the controls (p = 0.026, p = 0.018). The tested topical corneal alkali burn dose generated significant opacity and fibrosis in dog corneas without damaging the limbus as evidenced by histopathology, IHC, TEM, and OCT findings, and represents a viable large animal corneal fibrosis in vivo model. Additional in vivo SAHA dosing studies with larger sample size are warranted.

[EFFECT OF ANTIOXIDANTS ON ESOPHAGUS TISSUE REPAIR UPON EXPERIMENTAL CHEMICAL BURN FROM ACETIC ACID]

This work is an experimental study on 30 rabbits to determine the effect of antioxidants on the process of repair of the esophagus. Chemical agent was 46% acetic acid, a The antioxidant "Mexidol" were injected to core group of test animals in 2 weeks. Animals were taken from the experiment at 5, 14, 21, 30, 45 and 60 hours. We conducted morphometric study of histological exemplars, determining the number of inflammatory cells, epithelial thickness, the area of newformed blood vessels. In the study group we reported an improvement of reparative processes in the wall of the body: it was increased blood supply to the burn surface on 242% and more rapid relief of inflammatory processes on 117% (p < 0.05).

[Efficacy of epigallocatechin gallate in treatment of alkali burn injury of murine cornea]

OBJECTIVE

To evaluate the efficacy of epigallocatechin gallate (EGCG) in treatment of corneal alkali burn injury in mice.

METHODS

Corneal alkali burn injury was induced by sodium hydroxide method in C57BL/6J mice. The mice with cornea burns were treated intraperitoneally with EGCG solution or phosphate buffer solution (PBS) respectively. The healing of corneal epithelium, the formation of corneal neovascularization (CNV) and the inflammation reaction were assessed by slit -lamp microscopy and histological examination. Expression of vascular endothelial growth factor (VEGF) mRNA and protein in cornea was evaluated by real -time reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. Myeloperoxidase (MPO) assay was used to quantitatively evaluate the polymorphonuclear neutrophils (PMNs) infiltration in the corneas.

RESULTS

The healing rate of corneal epithelium in EGCG group was significantly higher than that of PBS group at d1, d3 and d7 after treatment (d1: 41.0%±13.0% vs 23.8%±7.6%; d3: 76.6%±7.5% vs 61.2%±6.8%; d7: 87.8%±8.5% vs 74.0%±9.1%; all P <0.05). The CNV scores and the number of CNV in the corneal sections of EGCG group were significantly lower than those of PBS group at d3, d7 and d14 after treatment (CNV score: d3: 1.1±0.5 vs 6.6±1.0; d7: 1.3±0. 3 vs 8.1±1.0; d14: 0.9±0.2 vs 9.2±1.1; CNV number: d3: 1.68±0.61 vs 2.92±0.95; d7: 4.80±1.36 vs 7.92±1.28; d14: 3.64±0.71 vs 5.88±0.76; all P<0.05) . The expression of VEGF protein at d3 (0.19±0.05 vs 0.45±0.08) and d7 (0.42±0.07 vs 0.84±0.09), the expression of VEGF mRNA at d1, d3 and d7 in EGCG group were significantly lower than those in PBS group (all P <0.05). Compared to PBS group, the inflammatory index at d3 (3.2±0.4 vs 3.7±0.5) and d7 (2.3±0.5 vs 4.0±0.0), the number of PMNs in the corneal sections and the MPO values at d3, d7 and d14 in EGCG group were significantly decreased (PMNs: d3: 34.5±15.7 vs 90.0±28.8; d7: 17.1±11.4 vs 54.9±25.9; d14: 12. 8±4.6 vs 39.0±17.9; all P <0.05).

CONCLUSION

In the murine corneal alkali burn model, intraperitoneal injection of EGCG solution can promote the healing of corneal epithelium, inhibit the formation of CNV and reduce the inflammatory cell infiltration in the corneas.

[Case of continuous trans-arterial calcium gluconate infusion using a direct arterial sphygmomanometry line that exhibited dramatic improvement of chemical burns on the fingers caused by hydrofluoric acid]

Hydrofluoric acid (HFA) is commonly used and many injuries occur on the upper extremities following exposure to HFA. The use of calcium gluconate (CG) -containing gel or local injections of CG are widely used for the initial treatment of HFA exposure. However, severe pain continues in some cases despite the treatment. There was a report that trans-arterial CG infusion could improve HFA burns, however, such treatment is not an established clinical procedure. A 30-year-old male presented at our hospital with severe pain in his left thumb. He had been cleaning tiles with an HFA-containing detergent. We diagnosed him with a chemical burn due to HFA exposure. Local CG injections were tried several times, but his terrible pain continued. Therefore, a direct arterial sphygmomanometry line was inserted from the left radial artery, and continuous transarterial CG injection was performed. His terrible pain dramatically improved. Direct arterial sphygmomanometry systems are widely used in the critical care field to monitor the hemodynamics and ICU staffs are used to dealing with it. Moreover, continuous saline infusion prevents the tube obstruction. Continuous CG infusion from a direct arterial sphygmomanometry line is simple and safe way to administer CG in HFA burns.

[Metabolic and organ protective properties of various infusion solutions and the choice of starting therapy in the pre-admission stage of acetic acid poisoning]

MATERIALS AND METHODS

We conducted an open prospective study in 60 patients (30 men and 30 women) with acetic acid poisoning. A randomization was performed on the groups, taking into account the tactics of infusion therapy: group I--15 patients who did not receive an infusion therapy at a pre-admission stage; group II--15 patients who received the infiusion therapy with solution of sodium chloride 0.9%; group III--15 patients who received the infusion therapy with modified gelatin (Gelofusinwn), group IV-15 patients who received the infusion therapy with reamberinum.

RESULTS

We found that the most favorable results were noted in patients of group IV in the early posttraumatic period.

Interventions for treating phosphorus burns

BACKGROUND

Phosphorus burns are rarely encountered in usual clinical practice and occur mostly in military and industrial settings. However, these burns can be fatal, even with minimal burn area, and are often associated with prolonged hospitalisation.

OBJECTIVES

To summarise the evidence of effects (beneficial and harmful) of all interventions for treating people with phosphorus burns.

SEARCH METHODS

In October 2013 for this first update we searched the Cochrane Wounds Group Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library);Ovid OLDMEDLINE; Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; EBSCO CINAHL and Conference Proceedings Citation Index - Science (CPCI-S). We did not apply any methodological filters or restrictions on the basis of study design, language, date of publication or publication status.

SELECTION CRITERIA

Any comparisons of different ways of managing phosphorus burns including, but not restricted, to randomised trials.

DATA COLLECTION AND ANALYSIS

We found two non-randomised comparative studies, both comparing patients treated with and without copper sulphate.

MAIN RESULTS

These two comparative studies provide no evidence to support the use of copper sulphate in managing phosphorus burns. Indeed the small amount of available evidence suggests that it may be harmful.

AUTHORS' CONCLUSIONS

First aid for phosphorus burns involves the common sense measures of acting promptly to remove the patient's clothes, irrigating the wound(s) with water or saline continuously, and removing phosphorus particles. There is no evidence that using copper sulphate to assist visualisation of phosphorus particles for removal is associated with better outcome, and some evidence that systemic absorption of copper sulphate may be harmful. We have so far been unable to identify any other comparisons relevant to informing other aspects of the care of patients with phosphorus burns. Future versions of this review will take account of information in articles published in languages other than English, which may contain additional evidence based on treatment comparisons.

[Hydrofluoric acid burns of the hands in the home environment: correct therapeutic approach]

The broad market penetration of products with components used primarily in the industrial sector requires the precise knowledge of their mechanism of action in order to perform a correct therapeutic approach. The article reports on three cases of domestic hydrofluoric acid burn that came to our Plastic Surgery Unit over the last three years. The treatment options are discussed in detail with emphasis on the importance of a constant update about such emerging diseases.

[Effect of dinitrosyl iron complexes on erythrocyte energy metabolism under thermal trauma conditions]

The effect of dinitrosyl iron complexes (DNIC) on the energy metabolism of erythrocytes under combined thermal trauma conditions has been studied on a group of 30 Wistar rats, which was divided into 3 groups: intact (n = 10), control (n = 10), and main (n = 10). Combined thermal trauma (skin burn + thermoinhalation damage) was modeled in animals of the control and main groups. Rats of control group received infusions of sodium chloride solution (n = 10) every day. Rats of the main group obtained infusions of DNIC solution in sodium chloride. Rat blood samples were characterized by the activity of lactate dehydrogenase in direct and reverse reaction, lactate level, and coefficients of the substrate provision and energy reactions balance. It was stated, that DNIC clearly normalized the energy metabolism of erythrocytes beginning with the third day after thermal trauma onset.

The effects of dimethyl sulfoxide on the acute phase of experimental acid and alkali corrosive esophageal burns

BACKGROUND, AIM

The aim of this study was to investigate the effects of dimethyl sulfoxide (DMSO) on the acute phase of experimental corrosive esophageal burns.

MATERIALS AND METHODS

Fifty male rats were allocated into five groups (control, acid burn, alkali burn, acid burn + DMSO and alkali burn + DMSO) of ten rats each. Acid and alkali burns were creating by burning the distal esophagus with 1 N hydrochloric acid and 50% sodium hydroxide solution, respectively. DMSO was applied intraperitoneally at 15 minutes after burn creation and then every 12 hours for four days. All animals were sacrificed at the end of the 7th day. Histopathological changes in esophageal tissue were scored by a single investigator who was blind to the burn group.

RESULTS

Application of DMSO resulted in a significant decrease in the severity of acute tissue damage as measured by macroscopic and microscopic assessments in both the acidic and alkaline esophagitis groups. The increased immunohistochemical Ki-67 proliferation index was significantly suppressed in the DMSO-treated alkaline esophagitis group, p < 0.05. Furthermore, the immunoreactivity of nuclear factor kappa B (NF-kB) was significantly reduced in both the acid and alkali DMSO-treated groups, p < 0.05.

CONCLUSIONS

DMSO reduced the acute phase symptoms and decreased the severity of tissue damage in both acidic and alkaline corrosive esophagitis.