Therapeutic effects of zerumbone in an alkali-burned corneal wound healing model

Comparison of Biomarkers Playing a Role in Pterygium Development in Pterygium and Recurrent Pterygium Tissues

Background/Objectives: Pterygium is a nonneoplastic elastotic degeneration characterized by subepithelial growth. It manifests as an ocular lesion originating from the bulbar conjunctiva, extending to the corneal surface, and reaching the visual axis in some cases. Although the exact cause is unknown, prolonged exposure to ultraviolet radiation is considered the most significant contributing factor. Chronic irritation and actinic damage are likely responsible for the typical fibrovascular reactions observed in pterygium. Additionally, growth factors, cytokines, and matrix metalloproteinases play roles in the pathogenesis of pterygium. This study compared recurrent and primary pterygium cases at the molecular level to gain new insights into the etiology of pterygium. Methods: Total protein was extracted from surgical samples of patients with primary and recurrent pterygium, and the levels of transforming growth factor beta 1 (TGF-β1), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), IL-8, and IL-10 were analyzed using the enzyme-linked immunosorbent assay technique. Target gene expression levels were analyzed using the ΔΔCt method after cDNA synthesis from isolated RNA, with normalization to GAPDH and quantification performed with SYBR Green PCR Master Mix. Results: Among the studied cytokines, IL-10 levels were higher in primary pterygium than in recurrent pterygium (722.0 ± 600.9/421.4 ± 266.8) (p = 0.0054). Other cytokines (IL-6, IL-8, IL-1β, and TGF-β1) were detected at similar levels in both primary and recurrent pterygium (p = 0.2986). Additionally, the TGF-β1 gene expression was found to be significantly upregulated in recurrent pterygium tissue compared to primary pterygium tissue (p = 0.034). Conclusions: This increase suggests that TGF-β1 may contribute to the recurrence mechanisms of pterygium through processes such as fibroblast activation and tissue remodeling. The higher levels of IL-10 in primary pterygium compared to recurrent pterygium indicate an enhanced early protective response aimed at limiting pterygium progression and controlling the inflammatory process.

The role of the JAK/STAT3 signaling pathway in acquired corneal diseases

Acquired corneal diseases such as dry eye disease (DED), keratitis and corneal alkali burns are significant contributors to vision impairment worldwide, and more effective and innovative therapies are urgently needed. The Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway plays an indispensable role in cell metabolism, inflammation and the immune response. Studies have shown that regulators of this pathway are extensively expressed in the cornea, inducing significant activation of JAK/STAT3 signaling in specific acquired corneal diseases. The activation of JAK/STAT3 signaling contributes to various pathophysiological processes in the cornea, including inflammation, neovascularization, fibrosis, and wound healing. In the context of DED, the hypertonic environment activates JAK/STAT3 signaling to stimulate corneal inflammation. Inflammation and injury progression in infectious keratitis can also be modulated by JAK/STAT3 signaling. Furthermore, JAK/STAT3 signaling is involved in every stage of corneal repair after alkali burns, including acute inflammation, angiogenesis and fibrosis. Treatments modulating JAK/STAT3 signaling have shown promising results in attenuating corneal damage, indicating its potential as a novel therapeutic target. Thus, this review emphasizes the multiple roles of the JAK/STAT3 signaling pathway in common acquired corneal disorders and summarizes the current achievements of JAK/STAT3-targeting therapy to provide new insights into future applications.

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/β-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.

Melatonin Inhibits VEGF-Induced Endothelial Progenitor Cell Angiogenesis in Neovascular Age-Related Macular Degeneration

Neovascular age-related macular degeneration (AMD) is described as abnormal angiogenesis in the retina and the leaking of fluid and blood that generates a huge, dark, blind spot in the center of the visual field, causing severe vision loss in over 90% of patients. Bone marrow-derived endothelial progenitor cells (EPCs) contribute to pathologic angiogenesis. Gene expression profiles downloaded from the eyeIntegration v1.0 database for healthy retinas and retinas from patients with neovascular AMD identified significantly higher levels of EPC-specific markers (CD34, CD133) and blood vessel markers (CD31, VEGF) in the neovascular AMD retinas compared with healthy retinas. Melatonin is a hormone that is mainly secreted by the pineal gland, and is also produced in the retina. Whether melatonin affects vascular endothelial growth factor (VEGF)-induced EPC angiogenesis in neovascular AMD is unknown. Our study revealed that melatonin inhibits VEGF-induced stimulation of EPC migration and tube formation. By directly binding with the VEGFR2 extracellular domain, melatonin significantly and dose-dependently inhibited VEGF-induced PDGF-BB expression and angiogenesis in EPCs via c-Src and FAK, NF-κB and AP-1 signaling. The corneal alkali burn model demonstrated that melatonin markedly inhibited EPC angiogenesis and neovascular AMD. Melatonin appears promising for reducing EPC angiogenesis in neovascular AMD.

Combined Silver Sulfadiazine Nanosuspension with Thermosensitive Hydrogel: An Effective Antibacterial Treatment for Wound Healing in an Animal Model

Introduction

Silver sulfadiazine (AgSD) is widely used in burn wound treatment due to its broad-spectrum antibacterial activity. However, its application in wound healing is greatly hindered by the low solubility of AgSD particles and their cellular cytotoxicity. Herein, we studied the safety and in vivo efficacy of nano-sized silver sulfadiazine loaded in poloxamer thermosensitive hydrogel (NS/Gel).

Methods

In NS/Gel, silver sulfadiazine was prepared into silver sulfadiazine nanosuspension (NS) to improve the solubility and enhance its antibacterial activity, whereas the poloxamer thermosensitive hydrogel was selected as a drug carrier of NS to achieve slow drug release and reduced cytotoxicity. The acute toxicity of silver sulfadiazine nanosuspension was first evaluated in healthy mice, and its median lethal dose (LD₅₀) was calculated by the modified Karber method. Furthermore, in vivo antibacterial effect and wound healing property of NS/Gel were evaluated on the infected deep second-degree burn wound mice model.

Results

The mortality ratio of mice was concentration-dependent, and the LD₅₀ for silver sulfadiazine nanosuspension was estimated to be 252.1 mg/kg (230.8 to 275.4 mg/kg, 95% confidence limit). The in vivo dosages used for burn wound treatment (40-50 mg/kg) were far below LD₅₀ (252.1 mg/kg). NS/Gel significantly accelerated wound healing in the deep second wound infection mice model, achieving > 85% wound contraction on day 14. Staphylococcus aureus in the wound region was eradicated after 7 days in NS/Gel group, while the bacterial colony count was still measurable in the control group. Histological analysis and cytokines measurement confirmed that the mice treated with NS/Gel exhibited well-organized epithelium and multiple keratinized cell layers compared to control groups with the modulated expression of IL-6, VEGF, and TGF-β.

Conclusion

The combination of silver sulfadiazine nanosuspension and thermo-responsive hydrogel has great potential in clinical burn wound treatment.

From bench to clinic: Emerging therapies for corneal scarring

Corneal diseases are one of the leading causes of moderate-to-severe visual impairment and blindness worldwide, after glaucoma, cataract, and retinal disease in overall importance. Given its tendency to affect people at a younger age than other blinding conditions such as cataract and glaucoma, corneal scarring poses a huge burden both on the individuals and society. Furthermore, corneal scarring and fibrosis disproportionately affects people in poorer and remote areas, making it a significant ophthalmic public health problem. Traditional medical strategies, such as topical corticosteroids, are not effective in preventing fibrosis or scars. Corneal transplantation, the only effective sight-restoring treatment for corneal scars, is curbed by challenges including a severe shortage of tissue, graft rejection, secondary conditions, cultural barriers, the lack of well-trained surgeons, operating rooms, and well-equipped infrastructures. Thanks to tremendous research efforts, emerging therapeutic options including gene therapy, protein therapy, cell therapy and novel molecules are in development to prevent the progression of corneal scarring and compliment the surgical options currently available for treating established corneal scars in clinics. In this article, we summarise the most relevant preclinical and clinical studies on emerging therapies for corneal scarring in recent years, showing how these approaches may prevent scarring in its early development.

Extracellular Matrix Deposition and Remodeling after Corneal Alkali Burn in Mice

Corneal transparency relies on the precise arrangement and orientation of collagen fibrils, made of mostly Type I and V collagen fibrils and proteoglycans (PGs). PGs are essential for correct collagen fibrillogenesis and maintaining corneal homeostasis. We investigated the spatial and temporal distribution of glycosaminoglycans (GAGs) and PGs after a chemical injury. The chemical composition of chondroitin sulfate (CS)/dermatan sulfate (DS) and heparan sulfate (HS) were characterized in mouse corneas 5 and 14 days after alkali burn (AB), and compared to uninjured corneas. The expression profile and corneal distribution of CS/DSPGs and keratan sulfate (KS) PGs were also analyzed. We found a significant overall increase in CS after AB, with an increase in sulfated forms of CS and a decrease in lesser sulfated forms of CS. Expression of the CSPGs biglycan and versican was increased after AB, while decorin expression was decreased. We also found an increase in KS expression 14 days after AB, with an increase in lumican and mimecan expression, and a decrease in keratocan expression. No significant changes in HS composition were noted after AB. Taken together, our study reveals significant changes in the composition of the extracellular matrix following a corneal chemical injury.

The potential protective effects of miR-497 on corneal neovascularization are mediated via macrophage through the IL-6/STAT3/VEGF signaling pathway

Corneal neovascularization (CoNV) can cause abnormal blood vessels to grow in the transparent cornea, leading to various sight-threatening eye diseases. MicroRNAs are known to play essential roles in the regulation of numerous biological functions. We try to clarify the role of a specific microRNA, miR‑497, which has been shown to regulate the growth of tumor cells and angiogenesis on the basis of available data. However, the association between miR-497 and vascularized cornea remains unclear. Therefore, it is urgently needed to understand the molecular mechanism of miR497 in the progress of corneal neovascularization. Animal model of CoNV was established in wildtype (WT) C57BL/6 mice, CRISPR/Cas9 mediated miR-497 knockout (KO) and overexpressed (TG) C57BL/6 mice. MiR-497, expressed in corneas, was actively involved in alkali burn-induced corneal neovascularization via targeting STAT3 and negatively regulating its expression, attenuating macrophage infiltration and M2 polarization. Knockdown of miR-497 enhanced the formation of corneal angiogenesis through targeting STAT3 and facilitating its expression, promoting recruitment of macrophages, while overexpression of miR-497 restrained blood vessel sprouting via regulating downstream STAT3 and VEGFA expression, reducing macrophage activation and inhibiting M2 polarization. Moreover, miR-497 knockout-mediated damage effect can be rescued through the inhibition of STAT3 signaling. Mechanically, miR-497 might serve as a potential strategy for pathological corneal neovascularization via macrophage through the IL-6/STAT3/VEGFA signaling pathway.

Promising Effects of Zerumbone on the Regulation of Tumor-promoting Cytokines Induced by TNF-α-activated Fibroblasts

Inflammation plays an important role in the development of several cancers. Inflammatory cytokines, including tumor necrosis factor-α (TNF-α), are associated with the induction of inflammation. Chronic inflammation contributes to the progression of cancer through several mechanisms, including increased cytokine production and activation of transcription factors, such as nuclear factor-κB (NF-κB). Zerumbone (ZER), a component of subtropical ginger (Zingiber zerumbet Smith), seems to have anti-inflammatory, anti-cancer, and antioxidant activities. In this study, we aimed to explore the protective function and mechanisms of ZER against TNF-α-induced cancer-promoting cytokines. We found that the viability of stimulated human fibroblast cell lines was reduced after treatment with ZER (IC₅₀=18 µmol/L), compared to un-stimulated fibroblasts (IC₅₀=40 µmol/L). Besides, ZER inhibited mRNA expression and protein secretion of transforming growth factor-β (TGF-β), interleukin-33 (IL-33), monocyte chemoattractant protein-1 (MCP-1), and stromal cell-derived factor 1 (SDF-1), which were produced by TNF-α-induced fibroblasts, as measured by quantitative real time-PCR (qRT-PCR) and ELISA assays. The mRNA expression levels of TGF-β, IL-33, SDF-1, and MCP-1 showed 8, 5, 2.5, and 4-fold reductions, respectively. Moreover, secretion of TGF-β, IL-33, SDF-1, and MCP-1 was reduced to 3.65±0.34 ng/mL, 6.3±0.26, 1703.6±295.2, and 5.02±0.18 pg/mL, respectively, compared to the untreated group. In addition, the conditioned media (CM) of TNF-α-stimulated fibroblasts increased the NF-κB expression in colorectal cancer cell lines (HCT-116 and Sw48), while in the vicinity of ZER, the expression of NF-κB was reversed. Considering the significant effects of ZER, this component can be used as an appropriate alternative herbal treatment for cancer-related chronic inflammation.

Dasatinib loaded nanostructured lipid carriers for effective treatment of corneal neovascularization

Dasa-NLC could significantly inhibit the corneal neovascularization.

Targeting Janus Kinases and Signal Transducer and Activator of Transcription 3 to Treat Inflammation, Fibrosis, and Cancer: Rationale, Progress, and Caution

Before it was molecularly cloned in 1994, acute-phase response factor or signal transducer and activator of transcription (STAT)3 was the focus of intense research into understanding the mammalian response to injury, particularly the acute-phase response. Although known to be essential for liver production of acute-phase reactant proteins, many of which augment innate immune responses, molecular cloning of acute-phase response factor or STAT3 and the research this enabled helped establish the central function of Janus kinase (JAK) family members in cytokine signaling and identified a multitude of cytokines and peptide hormones, beyond interleukin-6 and its family members, that activate JAKs and STAT3, as well as numerous new programs that their activation drives. Many, like the acute-phase response, are adaptive, whereas several are maladaptive and lead to chronic inflammation and adverse consequences, such as cachexia, fibrosis, organ dysfunction, and cancer. Molecular cloning of STAT3 also enabled the identification of other noncanonical roles for STAT3 in normal physiology, including its contribution to the function of the electron transport chain and oxidative phosphorylation, its basal and stress-related adaptive functions in mitochondria, its function as a scaffold in inflammation-enhanced platelet activation, and its contributions to endothelial permeability and calcium efflux from endoplasmic reticulum. In this review, we will summarize the molecular and cellular biology of JAK/STAT3 signaling and its functions under basal and stress conditions, which are adaptive, and then review maladaptive JAK/STAT3 signaling in animals and humans that lead to disease, as well as recent attempts to modulate them to treat these diseases. In addition, we will discuss how consideration of the noncanonical and stress-related functions of STAT3 cannot be ignored in efforts to target the canonical functions of STAT3, if the goal is to develop drugs that are not only effective but safe. SIGNIFICANCE STATEMENT: Key biological functions of Janus kinase (JAK)/signal transducer and activator of transcription (STAT)3 signaling can be delineated into two broad categories: those essential for normal cell and organ development and those activated in response to stress that are adaptive. Persistent or dysregulated JAK/STAT3 signaling, however, is maladaptive and contributes to many diseases, including diseases characterized by chronic inflammation and fibrosis, and cancer. A comprehensive understanding of JAK/STAT3 signaling in normal development, and in adaptive and maladaptive responses to stress, is essential for the continued development of safe and effective therapies that target this signaling pathway.

LRG1 promotes corneal angiogenesis and lymphangiogenesis in a corneal alkali burn mouse model

AIM

To investigate the potential effect and mechanism of leucine-rich α-2-glycoprotein-1 (LRG1) on corneal angiogenesis and lymphangiogenesis.

METHODS

Corneal neovascularization and lymphatics were induced by establishing alkali burn mouse model. Immunofluorescence staining was performed to detect the location of LRG1 in cornea tissues and to verify the source of LRG1-positive cells. Corneal whole-mount staining for CD31 (a panendothelial cell marker) and lymphatic endothelial hyluronan receptor-1 (LYVE-1; lymphatic marker) was performed to detect the growth of blood and lymphatic vessels after local application of exogenous LRG1 protein or LRG1 siRNA. In addition, expressions of the proangiogenic vascular endothelial growth factor (VEGF) related proteins were detected using Western blot analysis.

RESULTS

LRG1 was dramatically increased in alkali burned corneal stroma in both the limbal and central areas. LRG1-positive cells in the corneal stroma were mainly derived from Vimentin-positive cells. Local application of exogenous LRG1 protein not only aggravated angiogenesis but also lymphangiogenesis significantly (P<0.01). LRG1 group upregulated the levels of VEGF and the vascular endothelial growth factor receptor (VEGFR) family when compared with the phosphate-buffered saline (PBS) control group. We also found that LRG1-specific siRNA could suppress corneal angiogenesis and lymphangiogenesis when compared with the scramble siRNA-treated group (P<0.01).

CONCLUSION

LRG1 can facilitate corneal angiogenesis and lymphangiogenesis through heightening the stromal expression of VEGF-A, B, C, D and VEGFR-1, 2, 3; LRG1-specific siRNA can suppress corneal angiogenesis and lymphangiogenesis in corneal alkali burn mice.

Comparative Analysis of KGF-2 and bFGF in Prevention of Excessive Wound Healing and Scar Formation in a Corneal Alkali Burn Model

PURPOSE

Basic fibroblast growth factor (bFGF) is an effective drug for corneal injury. However, the explicit role of bFGF in corneal scar formation still remains unclear. Keratinocyte growth factor-2 (KGF-2) is associated with the treatment of wound healing. We aimed to compare the efficacy of bFGF and KGF-2 in prevention of excessive wound healing and consequent scar formation in a rat alkali burn model, which provides important clues on the significance of KGF-2 to be developed as a new drug for such injuries.

METHODS

The epithelial defect area was evaluated using fluorescein sodium at a concentration of 0.5%. The therapeutic effect of KGF-2 and bFGF on proliferation of rabbit corneal fibroblasts (RCFs) was evaluated by methylthiazoletetrazolium. RCF migration assays were performed with a modified scratch method. Activation of mitogen-activated protein kinase (MAPK) was evaluated by Western blot with specific antibodies.

RESULTS

All corneal wounds treated with KGF-2 were found closed within 7 days; however, the wounds treated with bFGF or phosphate buffer saline (PBS) required 14 days to close. RCFs treated with KGF-2 or bFGF showed similar dose-dependent proliferation. The KGF-2 group significantly promoted cell migration compared with the bFGF group. The KGF-2 group showed less expression of α-smooth muscle actin (SMA) and numbers of myofibroblasts compared with the bFGF group. Our findings suggested identification of cascade reaction of extracellular regulated protein kinases (ERK)1/2 and p38 signals in KGF-2- and bFGF-induced proliferation and migration of RCFs. In addition, KGF-2 showed stronger effects during ERK1/2 and p38 phosphorylation in methylthiazoletetrazolium proliferation assay and scratch migration assay.

CONCLUSIONS

KGF-2 exhibited better effects than bFGF in reepithelialization, acceleration of migration, and reduction of scar formation, which has potential to become a new drug to cure corneal injury.

Corneal Repair and Regeneration: Current Concepts and Future Directions

The cornea is a unique tissue and the most powerful focusing element of the eye, known as a window to the eye. Infectious or non-infectious diseases might cause severe visual impairments that need medical intervention to restore patients' vision. The most prominent characteristics of the cornea are its mechanical strength and transparency, which are indeed the most important criteria considerations when reconstructing the injured cornea. Corneal strength comes from about 200 collagen lamellae which criss-cross the cornea in different directions and comprise nearly 90% of the thickness of the cornea. Regarding corneal transparency, the specific characteristics of the cornea include its immune and angiogenic privilege besides its limbus zone. On the other hand, angiogenic privilege involves several active cascades in which anti-angiogenic factors are produced to compensate for the enhanced production of proangiogenic factors after wound healing. Limbus of the cornea forms a border between the corneal and conjunctival epithelium, and its limbal stem cells (LSCs) are essential in maintenance and repair of the adult cornea through its support of corneal epithelial tissue repair and regeneration. As a result, the main factors which threaten the corneal clarity are inflammatory reactions, neovascularization, and limbal deficiency. In fact, the influx of inflammatory cells causes scar formation and destruction of the limbus zone. Current studies about wound healing treatment focus on corneal characteristics such as the immune response, angiogenesis, and cell signaling. In this review, studied topics related to wound healing and new approaches in cornea regeneration, which are mostly related to the criteria mentioned above, will be discussed.

Dietary zerumbone, a sesquiterpene, ameliorates hepatotoxin-mediated acute and chronic liver injury in mice

Acute liver injury (ALI) is a life-threatening clinical syndrome. Long-lasting liver injury can lead to chronic hepatic inflammation and fibrogenic responses. Zerumbone (ZER), the main constituent of rhizomes of Zingiber zerumbet Smith, has a variety of functions including anticancer activity. We investigated the role of ZER on the progression of hepatotoxin-induced liver injury. Single or repeated injection of CCl₄ was used to induce acute or chronic liver injury, respectively. Mice were orally administered with ZER (10, 50 mg/kg) during the experimental period. Histopathologic analysis and serum biochemical levels revealed that ZER had hepatoprotective activities against ALI. Similar effects of ZER on injured livers were confirmed by analyses of inflammation and apoptosis-related genes. Western blot analysis showed that protein levels of apoptotic molecules were decreased, whereas antiapoptotic protein levels were conversely increased in injured livers treated with ZER. Furthermore, chronic liver injury and its associated fibrogenesis in mice were reduced by ZER treatment. These findings from our in vivo experiments further indicate that ZER could alleviate hepatocellular toxicity and inhibit activation of primary hepatic stellate cells. Our results suggest that ZER might have potential as a safe and prophylactic alternative to prevent acute and chronic liver injury.

Rhamnazin attenuates inflammation and inhibits alkali burn-induced corneal neovascularization in rats

The purpose of our study was to determine whether rhamnazin inhibits corneal neovascularization in the rat alkali burn model, and alleviates the inflammatory response of the cornea. Rhamnazin inhibited the proliferation of HUVEC cells in a dose-dependent manner, and it also inhibited the migration and luminal formation of HUVEC cells. 20 μM rhamnazin eye drops were applied to an animal model of corneal alkali burn neovascularization 4 times a day for 14 days. The corneal neovascularization in the rhamnazin group was obviously less than that in the PBS control group. In the rhamnazin group, the inflammatory index of the cornea decreased gradually over time, whereas the inflammatory index of the PBS group decreased only slightly with time. The corneal CNV area in the PBS group was significantly larger than that in the rhamnazin group. The expression level of VEGF protein of the rhamnazin group was lower than that in the PBS group, and the expression level of PEDF was significantly higher than that of the PBS group. Rhamnazin downregulated the expression of VEGFR2 protein and decreased the expression levels of p-STAT3, p-MAPK and p-Akt proteins. This study provides a new idea for the study of the molecular mechanism of corneal neovascularization.

The purpose of our study was to determine whether rhamnazin inhibits corneal neovascularization in the rat alkali burn model, and alleviates the inflammatory response of the cornea.