Development of an injectable oxidized dextran/gelatin hydrogel capable of promoting the healing of alkali burn-associated corneal wounds.

The cornea serves as an essential shield that protects the underlying eye from external conditions, yet it remains highly vulnerable to injuries that could lead to blindness and scarring if not promptly and effectively treated. Excessive inflammatory response constitute the primary cause of pathological corneal injury. This study aimed to develop effective approaches for enabling the functional repair of corneal injuries by combining nanoparticles loaded with anti-inflammatory agents and an injectable oxidized dextran/gelatin/borax hydrogel. The injectability and self-healing properties of developed hydrogels based on borate ester bonds and dynamic Schiff base bonds were excellent, improving the retention of administered drugs on the ocular surface. In vitro cellular assays and in vivo animal studies collectively substantiated the proficiency of probucol nanoparticle-loaded hydrogels to readily suppress proinflammatory marker expression and to induce the upregulation of anti-inflammatory mediators, thereby supporting rapid repair of rat corneal tissue following alkali burn-induced injury. As such, probucol nanoparticle-loaded hydrogels represent a prospective avenue to developing long-acting and efficacious therapies for ophthalmic diseases.

Adaptor protein 14-3-3zeta promotes corneal wound healing via regulating cell homeostasis, a potential novel therapy for corneal injury.

Severe corneal injury can lead to blindness even after prompt treatment. 14-3-3zeta, a member of an adaptor protein family, contributes to tissue repair by enhancing cellular viability and inhibiting fibrosis and inflammation in renal disease or arthritis. However, its role in corneal regeneration is less studied. In this study, filter disc of 2-mm diameter soaked in sodium hydroxide with a concentration of 0.5 N was placed at the center of the cornea for 30 s to establish a mouse model of corneal alkali injury. We found that 14-3-3zeta, which is mainly expressed in the epithelial layer, was upregulated following injury. Overexpression of 14-3-3zeta in ocular tissues via adeno-associated virus-mediated subconjunctival delivery promoted corneal wound healing, showing improved corneal structure and transparency. In vitro studies on human corneal epithelial cells showed that 14-3-3zeta was critical for cell proliferation and migration. mRNA-sequencing in conjunction with KEGG analysis and validation experiments revealed that 14-3-3zeta regulated the mRNA levels of ITGB1, PIK3R1, FGF5, PRKAA1 and the phosphorylation level of Akt, suggesting the involvement of the PI3K-Akt pathway in 14-3-3zeta-mediated tissue repair. 14-3-3zeta is a potential novel therapeutic candidate for treating severe corneal injury.

Trimebutine prevents corneal inflammation in a rat alkali burn model.

Alkaline burns to the cornea lead to loss of corneal transparency, which is essential for normal vision. We used a rat corneal alkaline burn model to investigate the effect of ophthalmic trimebutine solution on healing wounds caused by alkaline burns. Trimebutine, an inhibitor of the high-mobility group box 1-receptor for advanced glycation end products, when topically applied to the burned cornea, suppressed macrophage infiltration in the early phase and neutrophil infiltration in the late phase at the wound site. It also inhibited neovascularization and myofibroblast development in the late phase. Furthermore, trimebutine effectively inhibited interleukin-1ß expression in the injured cornea. It reduced scar formation by decreasing the expression of type III collagen. These findings suggest that trimebutine may represent a novel therapeutic strategy for corneal wounds, not only through its anti-inflammatory effects but also by preventing neovascularization.

Evaluation of the Treatment Effects of Conditioned Medium from Human Orbital Adipose-Derived Stem Cells in a Corneal Alkali Burn Rabbit Model.

Purpose: This study aimed to evaluate the effects of a new treatment-conditioned medium from human orbital adipose-derived stem cells (OASC-CM)-on corneal recovery after alkali burns in a rabbit model. Methods: The corneal alkali burn rabbit model was established and treated with OASC-CM, conditioned medium from human abdominal subcutaneous adipose-derived stem cells (ABASC-CM), and fresh control culture medium (con-CM) three times a day for 7 days, respectively. Subsequently, the treatment effects were evaluated and compared through clinical, histological, immunohistochemical, and cytokine evaluations. Results: Clinically, OASC-CM alleviated corneal opacity and edema and promoted recovery of corneal epithelium defect. Histologically and immunohistochemically, OASC-CM inhibited neovascularization, conjunctivalization, and immuno-inflammatory reaction, while promoting corneal regeneration and rearrangement. Increased secretion of interleukin-10 and inhibited protein levels of cluster of differentiation 45, interferon-γ, and tumor necrosis factor-α were observed in the alkali-burned cornea after OASC-CM treatment, which might be the relevant molecular mechanism. Conclusions: OASC-CM showed significant effects on the recovery of rabbit corneal alkali burns and eliminated immunological and ethical limitations, representing a new option for corneal wound treatment.

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.

Chemical (Alkali) Burn-Induced Neurotrophic Keratitis Model in New Zealand Rabbit Investigated Using Medical Clinical Readouts and In Vivo Confocal Microscopy (IVCM).

PURPOSE: Chemical eye injury is an acute emergency that can result in vision loss. Neurotrophic keratitis (NK) is the most common long-term manifestation of chemical injury. NK due to alkali burn affects ocular surface health and is one of its most common causes. Here, we established a rabbit model of corneal alkali burns to evaluate the severity of NK-associated changes. MATERIAL METHODS: Alkali burns were induced in NZ rabbits by treating the cornea with (i) a 5 mm circular filter paper soaked in 0.75 N NaOH for 10 s (Mild NK) and (ii) trephination using a guarded trephine (5 mm diameter and 150-micron depth), followed by alkali burn, with a 5 mm circular filter paper soaked in 0.75 N NaOH for 10 s (a severe form of NK). Immediately after, the cornea was rinsed with 10 mL of normal saline to remove traces of NaOH. Clinical features were evaluated on Day 0, Day 1, Day 7, Day 15, and Day 21 post-alkali burn using a slit lamp, Pentacam, and anterior segment optical coherence tomography (AS-OCT). NK-like changes in epithelium, sub-basal nerve plexus, and stroma were observed using in vivo confocal microscopy (IVCM), and corneal sensation were measured using an aesthesiometer post alkali injury. After 21 days, pro-inflammatory cytokines were evaluated for inflammation through ELISA. RESULTS: Trephination followed by alkali burn resulted in the loss of epithelial layers (manifested using fluorescein stain), extensive edema, and increased corneal thickness (550 µm compared to 380 µm thickness of control) evaluated through AS-OCT and increased opacity score in alkali-treated rabbit (80 compared to 16 controls). IVCM images showed complete loss of nerve fibers, which failed to regenerate over 30 days, and loss of corneal sensation-conditions associated with NK. Cytokines evaluation of IL6, VEGF, and MMP9 indicated an increased angiogenic and pro-inflammatory milieu compared to the milder form of NK and the control. DISCUSSION: Using clinical parameters, we demonstrated that the alkali-treated rabbit model depicts features of NK. Using IVCM in the NaOH burn animal model, we demonstrated a complete loss of nerve fibers with poor self-healing capability associated with sub-basal nerve degeneration and compromised corneal sensation. This pre-clinical rabbit model has implications for future pre-clinical research in neurotrophic keratitis.

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.

Composite Hydrogel Modulates Intrinsic Immune-Cascade Neovascularization for Ocular Surface Reconstruction after Corneal Chemical Injury.

Ocular alkali burns recruit neutrophils and triggers neutrophil extracellular trap (NET)-neovascularization cascade effects that limit ocular surface reconstruction and functional repair. However, effective inhibition of the release of neutrophil extracellular traps after a corneal chemical injury, coordination of intrinsic immunity with corneal repair, and exploration of more effective and non-invasive drug-delivery modes are still urgently needed. Using an in vitro coculture system, we found that an alkaline environment stimulates neutrophils to release NETs, which can be regulated by deoxyribonuclease I (DNase I). Inspired by this, we loaded DNase I, which effectively regulates NETs, onto chitosan nanoparticles and combined them with silk fibroin to construct a composite hydrogel that can sustainably regulate NETs. The hydrogel reduced neutrophil extracellular trap production by 50% and neovascularization by approximately 70% through sustained DNase I release after a corneal alkali burn. The complex hydrogel promotes ocular surface reconstruction by modulating the intrinsic immune-cascade neovascularization effect, providing a new research basis for the construction of nanobiomaterials that modulate pathological neovascularization.

Myeloid-derived suppressor cells ameliorate corneal alkali burn through IL-10-dependent anti-inflammatory properties.

This study aims to investigate the efficiency and the underlying mechanism of myeloid-derived suppressor cells (MDSCs) in corneal alkali burns (CAB). In the study, CD11b+ Gr-1+ cells from C57BL/6J mice bone marrow were cultured and induced. Cell activity and immunoregulatory function were assessed by flow cytometry in vitro. The optimal strategy of MDSCs therapy was assessed by slit-lamp microscopy, and flow cytometry in vivo. The therapeutic effects of MDSCs and the critical signaling pathway were investigated by hematoxylin-eosin (HE) staining, slit-lamp microscopy, flow cytometry, and immunofluorescence. The expression level of the NLRP3 inflammasome pathway was examined. The crucial biochemical parameters of MDSCs were examined by RNA-seq and qPCR to screen out the key regulators. The mechanism of MDSCs' therapeutic effects was explored using MDSCs with IL-10 knockout/rescue by slit-lamp microscopy, HE staining, and qPCR evaluation. The cell frequencies of macrophages and neutrophils in the cornea were examined by flow cytometry in vivo. The results demonstrated that the induced MDSCs meet the standard of phenotypic and functional characteristics. The treatment of 5 × 105 MDSCs conjunctival injection on alternate days significantly ameliorated the disease development, downregulated the NLRP3 inflammasome pathway, and decreased the cell frequencies of macrophages and neutrophils in vivo significantly. IL-10 was screened out to be the critical factor for MDSCs therapy. The therapeutic effects of MDSCs were impaired largely by IL-10 knock-out and saved by the IL-10 supplement. In conclusion, MDSCs therapy is a promising therapeutic solution for CAB. MDSCs fulfilled immunoregulatory roles for CAB by IL-10-dependent anti-inflammatory properties.

Collagen membrane loaded with doxycycline through hydroxypropyl chitosan microspheres for the early reconstruction of alkali-burned cornea.

Corneal alkali burn is one of the most devastating ophthalmic emergencies correlated with remarkable morbidity resulting in severe visual impairment. Appropriate intervention in the acute phase determines the eventual outcome for later corneal restoration treatment. Since the epithelium plays an essential role in inhibiting inflammation and promoting tissue repair, sustained anti-matrix metalloproteinases (MMPs) and pro-epithelialization are the prior remedies during the first week. In this study, a drug-loaded collagen membrane (Dox-HCM/Col) that could be sutured to overlay the burned cornea was developed to accelerate the early reconstruction. Doxycycline (Dox), a specific inhibitor of MMPs, was encapsulated in collagen membrane (Col) through hydroxypropyl chitosan microspheres (HCM) to develop Dox-HCM/Col, affording a preferable pro-epithelialization microenvironment and an in-situ controlled release. Results showed that loading HCM into Col prolonged the release time to 7 days, and Dox-HCM/Col could significantly suppress the expression of MMP-9 and -13 in vitro and in vivo. Furthermore, the membrane accelerated the corneal complete re-epithelialization and promoted early reconstruction within the first week. Overall, Dox-HCM/Col was a promising biomaterial membrane for treating alkali-burned cornea in the early stage, and our attempt may provide a clinically feasible method for the ocular surface reconstruction.

Pathogenesis of Alkali Injury-Induced Limbal Stem Cell Deficiency: A Literature Survey of Animal Models.

Limbal stem cell deficiency (LSCD) is a debilitating ocular surface disease that eventuates from a depleted or dysfunctional limbal epithelial stem cell (LESC) pool, resulting in corneal epithelial failure and blindness. The leading cause of LSCD is a chemical burn, with alkali substances being the most common inciting agents. Characteristic features of alkali-induced LSCD include corneal conjunctivalization, inflammation, neovascularization and fibrosis. Over the past decades, animal models of corneal alkali burn and alkali-induced LSCD have been instrumental in improving our understanding of the pathophysiological mechanisms responsible for disease development. Through these paradigms, important insights have been gained with regards to signaling pathways that drive inflammation, neovascularization and fibrosis, including NF-κB, ERK, p38 MAPK, JNK, STAT3, PI3K/AKT, mTOR and WNT/ß-catenin cascades. Nonetheless, the molecular and cellular events that underpin re-epithelialization and those that govern long-term epithelial behavior are poorly understood. This review provides an overview of the current mechanistic insights into the pathophysiology of alkali-induced LSCD. Moreover, we highlight limitations regarding existing animal models and knowledge gaps which, if addressed, would facilitate development of more efficacious therapeutic strategies for patients with alkali-induced LSCD.

Enhanced adipose-derived stem cells with IGF-1-modified mRNA promote wound healing following corneal injury.

The cornea serves as an important barrier structure to the eyeball and is vulnerable to injuries, which may lead to scarring and blindness if not treated promptly. To explore an effective treatment that could achieve multi-dimensional repair of the injured cornea, the study herein innovatively combined modified mRNA (modRNA) technologies with adipose-derived mesenchymal stem cells (ADSCs) therapy, and applied IGF-1 modRNA (modIGF1)-engineered ADSCs (ADSCmodIGF1) to alkali-burned corneas in mice. The therapeutic results showed that ADSCmodIGF1 treatment could achieve the most extensive recovery of corneal morphology and function when compared not only with simple ADSCs but also IGF-1 protein eyedrops, which was reflected by the healing of corneal epithelium and limbus, the inhibition of corneal stromal fibrosis, angiogenesis and lymphangiogenesis, and also the repair of corneal nerves. In vitro experiments further proved that ADSCmodIGF1 could more significantly promote the activity of trigeminal ganglion cells and maintain the stemness of limbal stem cells than simple ADSCs, which were also essential for reconstructing corneal homeostasis. Through a combinatorial treatment regimen of cell-based therapy with mRNA technology, this study highlighted comprehensive repair in the damaged cornea and showed the outstanding application prospect in the treatment of corneal injury.

A Novel Multi-Observation System to Study the Effects of Anterior Ocular Inflammation in Zinn's Zonule Using One Specimen.

Zinn's zonule is a fragile and thin tissue, and little is known about its pathogenesis. The aim of this study was to develop an experimental setup for a comprehensive analysis of Zinn's zonule. Rats were divided into two groups: a control group (n = 4) and an alkali injury group (n = 4). Seven days after injury, the eyes were enucleated, the anterior eye was dissected and embedded in gelatin, and macroscopic observations were made. The gelatin specimens were then embedded in paraffin and observed in detail by low-vacuum scanning electron microscopy, immunofluorescence, and quantitative reverse transcription polymerase chain reaction (RT-qPCR). The results show qualitative changes in Zinn's zonules in both macroscopic and microscopic observations. In addition, macrophage infiltration and increased matrix metalloproteinase 2 (MMP2) expression were observed in the injured group, consistent with the RT-qPCR results. The experimental system in this study allowed us to capture the morphological and molecular biological changes of Zinn's zonule and to gain insight into its pathogenesis. In conclusion, this study presents a new experimental setup for the comprehensive analysis of the rat Zinn's zonule. The results suggest that this system can be used in the future to study and analyze a variety of paraffin-embedded tissues and specimens.

Luteolin ameliorates cornea stromal collagen degradation and inflammatory damage in rats with corneal alkali burn.

Corneal alkali burn (AB) is a blindness-causing ocular trauma commonly seen in clinics. An excessive inflammatory reaction and stromal collagen degradation contribute to corneal pathological damage. Luteolin (LUT) has been studied for its anti-inflammatory effects. In this study, the effect of LUT on cornea stromal collagen degradation and inflammatory damage in rats with corneal alkali burn was investigated. After corneal alkali burn, rats were randomly assigned to the AB group and AB + LUT group and received an injection of saline and LUT (200 mg/kg) once daily. Subsequently, corneal opacity, epithelial defects, inflammation and neovascularization (NV) were observed and recorded on Days 1, 2, 3, 7 and 14 post-injury. The concentration of LUT in ocular surface tissues and anterior chamber, as well as the levels of collagen degradation, inflammatory cytokines, matrix metalloproteinases (MMPs) and their activity in the cornea were detected. Human corneal fibroblasts (HCFs) were co-cultured with interleukin (IL)-1ß and LUT. Cell proliferation and apoptosis were assessed by CCK-8 assay and flow cytometry respectively. Measurement of hydroxyproline (HYP) in culture supernatants was used to quantify the amount of collagen degradation. Plasmin activity was also assessed. ELISA or real-time PCR was used to detect the production of matrix metalloproteinases (MMPs), IL-8, IL-6 and monocyte chemotactic protein (MCP)-1. Furthermore, the immunoblot method was used to assess the phosphorylation of mitogen-activated protein kinases (MAPKs), transforming growth factor-ß-activated kinase (TAK)-1, activator protein-1 (AP-1) and inhibitory protein IκB-α. At last, immunofluorescence staining helped to develop nuclear factor (NF)-κB. LUT was detectable in ocular tissues and anterior chamber after intraperitoneal injection. An intraperitoneal injection of LUT ameliorated alkali burn-elicited corneal opacity, corneal epithelial defects, collagen degradation, NV, and the infiltration of inflammatory cells. The mRNA expressions of IL-1ß, IL-6, MCP-1, vascular endothelial growth factor (VEGF)-A, and MMPs in corneal tissue were downregulated by LUT intervention. And its administration reduced the protein levels of IL-1ß, collagenases, and MMP activity. Furthermore, in vitro study showed that LUT inhibited IL-1ß-induced type I collagen degradation and the release of inflammatory cytokines and chemokines by corneal stromal fibroblasts. LUT also inhibited the IL-1ß-induced activation of TAK-1, mitogen-activated protein kinase (MAPK), c-Jun, and NF-κB signaling pathways in these cells. Our results demonstrate that LUT inhibited alkali burn-stimulated collagen breakdown and corneal inflammation, most likely by attenuating the IL-1ß signaling pathway. LUT may therefore prove to be of clinical value for treating corneal alkali burns.

Liposome-trimethyl chitosan nanoparticles codeliver insulin and siVEGF to treat corneal alkali burns by inhibiting ferroptosis.

Alkali burns are potentially blinding corneal injuries. Due to the lack of available effective therapies, the prognosis is poor. Thus, effective treatment methods for corneal alkali burns are urgently needed. Codelivery nanoparticles (NPs) with characteristics such as high bioavailability and few side effects have been considered effective therapeutic agents for ocular diseases. In this study, we designed a new combination therapy using liposomes and trimethyl chitosan (TMC) for the codelivery of insulin (INS) and vascular endothelial growth factor small interfering RNA (siVEGF) to treat alkali-burned corneas. We describe the preparation and characterization of siVEGF-TMC-INS-liposome (siVEGF-TIL), drug release characteristics, intraocular tracing, pharmacodynamics, and biosafety. We found that siVEGF-TIL could inhibit oxidative stress, inflammation, and the expression of VEGF in vitro and effectively maintained corneal transparency, accelerated epithelialization, and inhibited corneal neovascularization (CNV) in vivo. Morever, we found that the therapeutic mechanism of siVEGF-TIL is possibly relevant to the inhibition of the ferroptosis signaling pathway by metabolomic analysis. In general, siVEGF-TIL NPs could be a safe and effective therapy for corneal alkali burn.

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.

The early association of water irrigation with negative pressure wound therapy does not more efficiently reduce the depth of the alkali infiltration progress into the burn.

Water irrigation is an efficacious decontaminating method for dermis exposures to corrosive agents and hence has been widely applied to treat especially alkali burns. Nevertheless, once alkali has infiltrated the deep subcutaneous tissue, washing the tissue surface with water irrigation does not attenuate the damage progress. Therefore, significant efforts have been devoted to promising strategies aimed at removing the deeply infiltrated lye. According to a recent report, the negative pressure wound therapy (NPWT) reduces the pH value of the exudate from alkali-provoked burns thus accelerating wound healing. However, it remains to be ascertained whether or not NPWT coupled with water irrigation, that is, iNPWT, more effectively hinders the alkali injury deepening. In this study, we compared the effectiveness of an early application of water irrigation with or without NPWT in preventing the progressive deepening of the alkali burn in an animal model. Our histological examination results showed no appreciable difference in tissue injury depth, dermal retention, inflammatory cell infiltration, re-epithelization, and cellular function between iNPWT and water irrigation alone treatments. Thus, our results prove that the more expensive NPWT coupled with water irrigation does not more effectively hinder the alkali's injury deepening. Hence, iNPWT use should be more cautious in clinical practice.

Inhibitory effect of miR-497 on corneal neovascularization and its regulation mechanism targeting STAT3 / 中华实验眼科杂志

Objective:To investigate the role of microRNA (miR)-497 in the formation of corneal neovascularization (CNV) induced by alkali burn and its mechanism.Methods:Forty-two wild type (WT) C57BL/6 mice aged 6 to 8 weeks, 42 CRISPR/Cas9 mediated miR-497 knockout (KO) and 42 CRISPR/Cas9 mediated overexpression transgenic (TG) C57BL/6 mice were selected and assigned as WT group, KO group and TG group, respectively.The corneal alkali burn model was established.At 3, 7, 14 and 21 days after modeling, corneal epithelium damage and stromal turbidity were scored according to slit lamp microscopy.The area of neovascularization was measured.Corneal structural changes and expression of inflammatory cells were observed by histopathological staining.The expression of CD31 in corneal tissues was detected by immunohistochemistry staining.The targeted binding relationship between miR-497 and signal transducer and activator of transcription 3 (STAT3) was detected by luciferase reporter assay.The relative expressions of miR-497, vascular endothelial growth factor A (VEGFA), tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β and macrophage inflammatory protein (MCP)-1 mRNA were detected by real-time quantitative PCR.At 14 days following modeling, the expression of STAT3 and p-STAT3 proteins in mice corneal tissues was detected by Western blot.The use and care of animals complied with the ARVO statement.The study protocol was approved by the Ethics Committee of Renmin Hospital of Wuhan University (No.2019K-K010).Results:Corneal injury, inflammatory cell infiltration and CNV occurred in mice cornea after alkali burn.Corneal epithelial injury score, corneal stromal turbidity score and CNV area increased first and reached the peak on the 14th day after modeling, and then decreased.There were significant differences in corneal epithelial injury score, corneal stromal turbidity score, CNV area and number of CD31-positive cells among various time points after alkali burn ( Fgroup=49.19, 34.56, 44.56, 77.56; all at P<0.01; Ftime=51.62, 65.62, 71.32, 46.12; all at P<0.01). Corneal epithelial injury score, corneal stromal turbidity score, CNV area and the number of CD31-positive cells were greater in KO group at various time points than in WT and TG groups, and those in WT group were greater than in TG group (all at P<0.05). In WT STAT3 co-transfected cells, the luciferase activity of the miR-497 group was significantly lower than that of the miR-negative control group and normal control group (both at P<0.05). In mutant STAT3-transfected cells, there was no significant difference in luciferase activity among all groups ( F=0.69, P=0.56). On the 14th day after modeling, the relative expression levels of miR-497 in corneal tissue of WT, KO and TG groups were 0.68±0.11, 0.41±0.06 and 1.05±0.14, respectively, which were significantly lower than 1.00±0.04, 0.56±0.07 and 1.34±0.11 before modeling (all at P<0.01). The relative expressions of STAT3 and p-STAT3 were higher in KO group than in WT and TG groups, and were lower in TG group than in WT group, and the differences were statistically significant (all at P<0.05). The expressions of VEGFA, TNF-α, IL-6, IL-1β and MCP-1 mRNA at various time points after modeling in various groups were significantly higher than before modeling, which were higher in KO group than in WT and TG groups and were lower in TG group than in WT group, and the differences were statistically significant (all at P<0.01). Conclusions:MiR-497 inhibits corneal inflammation and CNV formation induced by alkali burn.It might inhibit the activation of the inflammation signal pathway via targeting STAT3.

The Silent Threat-Alkali Foot Burn: A Case Report.

Despite current workplace protection measures, chemical burn accidents are not uncommon. Among these, alkali burn is the most challenging due to its silent behaviour and aggressive mechanism. Characterized by its initial painless onset, allowing a prolonged exposure, it tends to result in deeper and more destructive burns, creating major reconstructive and therapeutic challenges. This case concerns a 53-year-old male who sustained a full thickness burn of his left instep foot after prolonged contact with an alkali substance. The wound was submitted to several surgical debridement procedures, with preservation of the major tendinous and vascular-nervous structures. The skin defect was then repaired with skin graft. Early recognition and prompt management with copious and prolonged wound irrigation is paramount. As in this type of burn it is difficult to initially assess its true depth, even after initial surgical debridement, a more cautious approach is recommended. Chronic pain is associated with chemical burns and it should be treated early in the process with the use of multimodal analgesia in order to prevent future complications. No matter the absence of major complaints in the 4 week-postoperative evaluation, the possible long-term consequences are still unknown. Despite the prolonged exposure time and the initial presentation with a deep burn, after several surgical debridement procedures, preservation of major tendon and neurovascular structures was assured, which allowed a plain approach for reconstruction of the wound with a skin graft. The case illustrates different challenges associated with evaluation and treatment of patients with deep alkali burns. Also, usage auditing and awareness of regular users appear to be essential.

Les brûlures chimiques au travail restent relativement fréquentes malgré les mesures de protection. Les atteintes par agent alcalin sont particulièrement problématiques car elles sont insidieuses bien que très destructrices. Le temps de contact est prolongé et les destructions sont majeures, posant de difficiles problèmes de reconstruction, en raison de leur caractère initialement indolore. Nous présentons le cas d'un homme de 53 ans victime d'une brûlure du cou de pied gauche après contact prolongé avec un agent alcalin. Les excisions successives ont permis de préserver les éléments nobles et de greffer secondairement la zone touchée. Il est indispensable de diagnostiquer précisément l'atteinte et de laver la région atteinte à grande eau. La profondeur réelle est difficile à apprécier initialement si bien que les excisions doivent être prudentes. Les douleurs chroniques ne sont pas rares dans ces cas et peuvent être prévenues par la qualité de l'analgésie initiale, multimodale. A un mois, le patient ne se plaint de rien, ce qui ne préjuge pas de complications plus tardives. Malgré un temps de contact prolongé et un aspect initial profond, les éléments nobles on pu être préservés, permettant une couverture par simple greffe. Ce cas illustre les difficultés dans le diagnostic et le traitement des brûlures profondes par base. Il est essentiel d'éduquer et surveiller les usagers réguliers de ces produits.