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Diabetic eye disease (DED) encompasses a range of ocular complications arising from diabetes mellitus, including diabetic retinopathy, diabetic macular edema, diabetic keratopathy, diabetic cataract, and glaucoma. These conditions are leading causes of visual impairments and blindness, especially among working-age adults. Despite advancements in our understanding of DED, its underlying pathophysiological mechanisms remain incompletely understood. Chronic hyperglycemia, oxidative stress, inflammation, and neurodegeneration play central roles in the development and progression of DED, with immune-mediated processes increasingly recognized as key contributors. This review provides a comprehensive examination of the complex interactions between immune cells, inflammatory mediators, and signaling pathways implicated in the pathogenesis of DED. By delving in current research, this review aims to identify potential therapeutic targets, suggesting directions of research for future studies to address the immunopathological aspects of DED. [ABSTRACT FROM AUTHOR]

AIMS/HYPOTHESIS: Diabetes is associated with epigenetic modifications including DNA methylation and miRNA changes. Diabetic complications in the cornea can cause persistent epithelial defects and impaired wound healing due to limbal epithelial stem cell (LESC) dysfunction. In this study, we aimed to uncover epigenetic alterations in diabetic vs non-diabetic human limbal epithelial cells (LEC) enriched in LESC and identify new diabetic markers that can be targeted for therapy to normalise corneal epithelial wound healing and stem cell expression. METHODS: Human LEC were isolated, or organ-cultured corneas were obtained, from autopsy eyes from non-diabetic (59.87±20.89 years) and diabetic (71.93±9.29 years) donors. The groups were not statistically different in age. DNA was extracted from LEC for methylation analysis using Illumina Infinium 850K MethylationEPIC BeadChip and protein was extracted for Wnt phospho array analysis. Wound healing was studied using a scratch assay in LEC or 1-heptanol wounds in organ-cultured corneas. Organ-cultured corneas and LEC were transfected with WNT5A siRNA, miR-203a mimic or miR-203a inhibitor or were treated with recombinant Wnt-5a (200 ng/ml), DNA methylation inhibitor zebularine (1-20 µmol/l) or biodegradable nanobioconjugates (NBCs) based on polymalic acid scaffold containing antisense oligonucleotide (AON) to miR-203a or a control scrambled AON (15-20 µmol/l). RESULTS: There was significant differential DNA methylation between diabetic and non-diabetic LEC. WNT5A promoter was hypermethylated in diabetic LEC accompanied with markedly decreased Wnt-5a protein. Treatment of diabetic LEC and organ-cultured corneas with exogenous Wnt-5a accelerated wound healing by 1.4-fold (p

Corneal epithelial defects are one of the most common ocular disorders. Restoring corneal integrity is crucial to reduce pain and regain function, but in cases of neurotrophic or desensitized corneas, healing can be significantly delayed. Treating neurotrophic corneas is challenging for ophthalmologists, and surgical intervention is often indicated to manage refractory cases that are unresponsive to medical therapy. Over the last decade, as more expensive therapeutics reach the market, topical insulin has returned to the forefront as an affordable option to improve corneal wound healing. There is still a paucity of data on the use and the efficacy of topical insulin, with no consensus regarding its indications, preparation, or posology. Here we review the literature on topical insulin for corneal and ocular surface pathologies, with a focus on the current evidence, its mechanisms of action, and its safety profile. Additionally, we share our experience in the field and provide a potential framework for future research. [ABSTRACT FROM AUTHOR]

Abstract Introduction In recent years, insulin eye drops have attracted increasing attention from researchers and ophthalmologists. The aim of this study was to investigate the efficacy and possible mechanism of action of insulin eye drops in diabetic mice with corneal wounds. Methods A type 1 diabetes model was induced, and a corneal epithelial injury model of 2.5 mm was established. We used corneal fluorescein staining, hematoxylin-eosin (H-E) staining and the Cochet-Bonnet esthesiometer to examine the process of wound healing. Subsequently, the expression levels of Ki-67, IL-1β, β3-tubulin and neuropeptides, including substance P (SP) and calcitonin gene-related peptide (CGRP), were examined at 72 h after corneal injury. Results Fluorescein staining demonstrated an acceleration of the recovery of corneal epithelial injury in diabetic mice compared with the saline treatment, which was further evidenced by the overexpression of Ki-67. Moreover, 72 h of insulin application attenuated the expression of inflammatory cytokines and neutrophil infiltration. Remarkably, the results demonstrated that topical insulin treatment enhanced the density of corneal epithelial nerves, as well as neuropeptide SP and CGRP release, in the healing cornea via immunofluorescence staining. Conclusions Our results indicated that insulin eye drops may accelerate corneal wound healing and decrease inflammatory responses in diabetic mice by promoting nerve regeneration and increasing levels of neuropeptides SP and CGRP.

Abstract To analyze the changing trend of CH and CRF values under different influencing factors in T2DM patients. A total of 650 patients with T2DM were included. We discovered that the course of T2DM, smoking history, BMI, and FBG, DR, HbA1c, TC, TG, and LDL-C levels were common risk factors for T2DM, while HDL-C levels were a protective factor. Analyzing the CH and CRF values according to the course of diabetes, we discovered that as T2DM continued to persist, the values of CH and CRF gradually decreased. Moreover, with the increase in FBG levels and the accumulation of HbA1c, the values of CH and CRF gradually decreased. In addition, in patients with HbA1c (%) > 12, the values of CH and CRF decreased the most, falling by 1.85 ± 0.33 mmHg and 1.28 ± 0.69 mmHg, respectively. Compared with the non-DR group, the CH and CRF values gradually decreased in the mild-NPDR, moderate-NPDR, severe-NPDR and PDR groups, with the lowest CH and CRF values in the PDR group. In patients with T2DM, early measurement of corneal biomechanical properties to evaluate the change trend of CH and CRF values in different situations will help to identify and prevent diabetic keratopathy in a timely manner.

Diabetes mellitus (DM) is a chronic metabolic disorder marked by hyperglycemia due to defects in insulin secretion, action, or both, with a global prevalence that has tripled in recent decades. This condition poses significant public health challenges, affecting individuals, healthcare systems, and economies worldwide. Among its numerous complications, ocular surface disease (OSD) is a significant concern, yet understanding its pathophysiology, diagnosis, and management remains challenging. This review aims to explore the epidemiology, pathophysiology, clinical manifestations, diagnostic approaches, and management strategies of diabetes-related OSD. The ocular surface, including the cornea, conjunctiva, and associated structures, is vital for maintaining eye health, with the lacrimal functional unit (LFU) playing a crucial role in tear film regulation. In DM, changes in glycosaminoglycan metabolism, collagen synthesis, oxygen consumption, and LFU dysfunction contribute to ocular complications. Persistent hyperglycemia leads to the expression of cytokines, chemokines, and cell adhesion molecules, resulting in neuropathy, tear film abnormalities, and epithelial lesions. Recent advances in molecular research and therapeutic modalities, such as gene and stem cell therapies, show promise for managing diabetic ocular complications. Future research should focus on pathogenetically oriented therapies for diabetic neuropathy and keratopathy, transitioning from animal models to clinical trials to improve patient outcomes. [ABSTRACT FROM AUTHOR]

Introduction: In recent years, insulin eye drops have attracted increasing attention from researchers and ophthalmologists. The aim of this study was to investigate the efficacy and possible mechanism of action of insulin eye drops in diabetic mice with corneal wounds. Methods: A type 1 diabetes model was induced, and a corneal epithelial injury model of 2.5 mm was established. We used corneal fluorescein staining, hematoxylin-eosin (H-E) staining and the Cochet-Bonnet esthesiometer to examine the process of wound healing. Subsequently, the expression levels of Ki-67, IL-1β, β3-tubulin and neuropeptides, including substance P (SP) and calcitonin gene-related peptide (CGRP), were examined at 72 h after corneal injury. Results: Fluorescein staining demonstrated an acceleration of the recovery of corneal epithelial injury in diabetic mice compared with the saline treatment, which was further evidenced by the overexpression of Ki-67. Moreover, 72 h of insulin application attenuated the expression of inflammatory cytokines and neutrophil infiltration. Remarkably, the results demonstrated that topical insulin treatment enhanced the density of corneal epithelial nerves, as well as neuropeptide SP and CGRP release, in the healing cornea via immunofluorescence staining. Conclusions: Our results indicated that insulin eye drops may accelerate corneal wound healing and decrease inflammatory responses in diabetic mice by promoting nerve regeneration and increasing levels of neuropeptides SP and CGRP. [ABSTRACT FROM AUTHOR]

Diabetic eye disease (DED) encompasses a range of ocular complications arising from diabetes mellitus, including diabetic retinopathy, diabetic macular edema, diabetic keratopathy, diabetic cataract, and glaucoma. These conditions are leading causes of visual impairments and blindness, especially among working-age adults. Despite advancements in our understanding of DED, its underlying pathophysiological mechanisms remain incompletely understood. Chronic hyperglycemia, oxidative stress, inflammation, and neurodegeneration play central roles in the development and progression of DED, with immune-mediated processes increasingly recognized as key contributors. This review provides a comprehensive examination of the complex interactions between immune cells, inflammatory mediators, and signaling pathways implicated in the pathogenesis of DED. By delving in current research, this review aims to identify potential therapeutic targets, suggesting directions of research for future studies to address the immunopathological aspects of DED.

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes, with several underlying pathophysiological mechanisms, some of which are still uncertain. The cornea is an avascular tissue and sensitive to hyperglycemia, resulting in several diabetic corneal complications including delayed epithelial wound healing, recurrent erosions, neuropathy, loss of sensitivity, and tear film changes. The manifestation of DPN in the cornea is referred to as diabetic neurotrophic keratopathy (DNK). Recent studies have revealed that disturbed epithelial-neural-immune cell interactions are a major cause of DNK. The epithelium is supplied by a dense network of sensory nerve endings and dendritic cell processes, and it secretes growth/neurotrophic factors and cytokines to nourish these neighboring cells. In turn, sensory nerve endings release neuropeptides to suppress inflammation and promote epithelial wound healing, while resident immune cells provide neurotrophic and growth factors to support neuronal and epithelial cells, respectively. Diabetes greatly perturbs these interdependencies, resulting in suppressed epithelial proliferation, sensory neuropathy, and a decreased density of dendritic cells. Clinically, this results in a markedly delayed wound healing and impaired sensory nerve regeneration in response to insult and injury. Current treatments for DPN and DNK largely focus on managing the severe complications of the disease. Cell-based therapies hold promise for providing more effective treatment for diabetic keratopathy and corneal ulcers.

The relationship between diabetes mellitus and ocular complications has been extensively studied by many authors. Diabetic keratopathy has already been well characterized and defined as a clinical entity. This review focuses on exploring corneal epithelial changes in diabetic patients, aiming to provide a pragmatic overview of the existing knowledge on this topic. The paper systematically examines alterations in corneal epithelial structure and their impact on diabetic patients. Advanced imaging techniques are also discussed for their role in precise characterization and improved diagnostics. Additionally, the paper explores the mechanisms behind corneal epithelial changes in diabetes, looking at factors such as hyperglycemia, oxidative stress, and Advanced Glycation End-Products. The impact of altered corneal epithelial integrity on barrier function and susceptibility to external issues is considered, addressing potential links to heightened proteolytic enzyme activities and delayed wound healing observed in diabetic individuals. The review also covers the practical implications of corneal epithelial changes, including the association with corneal erosions, persistent epithelial defects, and an increased risk of dry eye syndrome in diabetic patients. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is one of the most prevalent diseases globally, and its prevalence is rapidly increasing. Most patients with a long-term history of DM present with some degree of keratopathy (DK). Despite its high incidence, the underlying inflammatory mechanism of DK has not been elucidated yet. For further insights into the underlying immunopathologic processes, we utilized streptozotocin-induced mice to model type 1 DM (T1D) and B6.Cg-Lepob/J mice to model type 2 DM (T2D). We evaluated the animals for the development of clinical manifestations of DK. Four weeks post-induction, the total frequencies of corneal CD45+CD11b+Ly-6G− myeloid cells, with enhanced gene and protein expression levels for the proinflammatory cytokines TNF-α and IL-1β, were higher in both T1D and T2D animals. Additionally, the frequencies of myeloid cells/mm2 in the sub-basal neural plexus (SBNP) were significantly higher in T1D and T2D compared to non-diabetic mice. DK clinical manifestations were observed four weeks post-induction, including significantly lower tear production, corneal sensitivity, and epitheliopathy. Nerve density in the SBNP and intraepithelial terminal endings per 40x field were lower in both models compared to the normal controls. The findings of this study indicate that DM alters the immune quiescent state of the cornea during disease onset, which may be associated with the progressive development of the clinical manifestations of DK. [ABSTRACT FROM AUTHOR]

Diabetic keratopathy (DK) is a common ocular complication of diabetes, characterized by alteration of the normal wound-healing mechanism, reduction of epithelial hemidesmosomes, disruption of the basement membrane, impaired barrier function, reduced corneal sensitivity, corneal ulcers, and corneal edema. The limited number of clinical studies do not allow a full characterization of the pathophysiology of DK and, until now, effective therapeutic approaches have not been available. However, in recent years, neuropeptides gained great attention for their biochemical characteristics and therapeutic potential. This review focuses on the role of neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the eye and, in particular, in the cornea, in physiological conditions, or during DK, by providing an overview of this diabetes mellitus complication. [ABSTRACT FROM AUTHOR]

Continuous replenishment of the corneal epithelium is pivotal for maintaining optical transparency and achieving optimal visual perception. This dynamic process is driven by limbal epithelial stem cells (LESCs) located at the junction between the cornea and conjunctiva, which is otherwise known as the limbus. In patients afflicted with diabetes, hyperglycemia-induced impairments in corneal epithelial regeneration results in persistent epithelial and other defects on the ocular surface, termed diabetic keratopathy (DK), which progressively diminish vision and quality of life. Reports of delayed corneal wound healing and the reduced expression of putative stem cell markers in diabetic relative to healthy eyes suggest that the pathogenesis of DK may be associated with the abnormal activity of LESCs. However, the precise role of these cells in diabetic corneal disease is poorly understood and yet to be comprehensively explored. Herein, we review existing literature highlighting aberrant LESC activity in diabetes, focusing on factors that influence their form and function, and emerging therapies to correct these defects. The consequences of malfunctioning or depleted LESC stocks in DK and limbal stem cell deficiency (LSCD) are also discussed. These insights could be exploited to identify novel targets for improving the management of ocular surface complications that manifest in patients with diabetes. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is a chronic metabolic disorder marked by hyperglycemia due to defects in insulin secretion, action, or both, with a global prevalence that has tripled in recent decades. This condition poses significant public health challenges, affecting individuals, healthcare systems, and economies worldwide. Among its numerous complications, ocular surface disease (OSD) is a significant concern, yet understanding its pathophysiology, diagnosis, and management remains challenging. This review aims to explore the epidemiology, pathophysiology, clinical manifestations, diagnostic approaches, and management strategies of diabetes-related OSD. The ocular surface, including the cornea, conjunctiva, and associated structures, is vital for maintaining eye health, with the lacrimal functional unit (LFU) playing a crucial role in tear film regulation. In DM, changes in glycosaminoglycan metabolism, collagen synthesis, oxygen consumption, and LFU dysfunction contribute to ocular complications. Persistent hyperglycemia leads to the expression of cytokines, chemokines, and cell adhesion molecules, resulting in neuropathy, tear film abnormalities, and epithelial lesions. Recent advances in molecular research and therapeutic modalities, such as gene and stem cell therapies, show promise for managing diabetic ocular complications. Future research should focus on pathogenetically oriented therapies for diabetic neuropathy and keratopathy, transitioning from animal models to clinical trials to improve patient outcomes.

Corneal epithelial abnormality is a common manifestation of diabetic keratopathy and leads to delayed epithelial wound healing. The Wnt/ß-catenin signaling pathway participates in the development, differentiation and stratification of corneal epithelial cells. The present study compared the expression of Wnt/ß-catenin signaling pathway related factors, including Wnt7a, ß-catenin, cyclin D1 and phosphorylated (p-) glycogen synthase kinase 3 ß (Gsk3b) between normal and diabetic mouse corneas, by reverse transcription-quantitative PCR, western blotting and immunofluorescence staining. It was found that the expression of the Wnt/ß-catenin signaling pathway related factors was downregulated in diabetic corneas. Upon corneal epithelium scraping, the wound healing rate was significantly increased in diabetic mice after topical treatment with lithium chloride. After further investigation, significantly upregulated levels of Wnt7a, ß-catenin, cyclin D1 and p-Gsk3b were found in the diabetic group 24 h after treatment, accompanied by ß-catenin nuclear translocation observed by immunofluorescence staining. These results suggest that active Wnt/ß-catenin pathway can promote diabetic corneal epithelial wound healing. [ABSTRACT FROM AUTHOR]

The IL-36 cytokines are known to play various roles in mediating the immune and inflammatory response to tissue injury in a context-dependent manner. This study investigated the role of IL-36R signaling in mediating epithelial wound healing in normal (NL) and diabetic (DM) C57BL/6 mouse corneas. The rate of epithelial wound closure was significantly accelerated in IL-36 receptor-deficient (IL-36R−/−) compared to wild-type (WT) mice. Wounding increased IL-36α and -36γ but repressed IL-36R antagonist (IL-36Ra) expression in B6 mouse corneal epithelial cells. The wound-induced proinflammatory cytokines CXCL1 and CXCL2 were dampened, while the antimicrobial peptides (AMPs) S100A8 and A9 were augmented in IL-36R−/− mouse corneas. Intriguingly, the expression of AMP LCN2 was augmented at the mRNA level. LCN2 deficiency resulted in an acceleration of epithelial wound healing. IL-36R deficiency also greatly increased the healing rate of the corneal epithelial wound in DM mice. IL-36R deficiency also suppressed IL-1β, IL-1Ra, and ICAM expression in unwounded-DM mice and wounded NL corneas. Opposing IL-1β and ICAM, the expression of IL-Ra in DM corneas of IL-36R−/− mice was augmented. The presence of recombinant IL-1Ra and IL-36Ra accelerated epithelial wound closure in T1DM corneas of B6 mice. Our study revealed an unprecedented role of IL-36R signaling in controlling corneal epithelial wound healing in normal (NL) and diabetic (DM) mice. Our data suggest that IL-36Ra, similar to IL-1Ra, might be a therapeutic reagent for improving wound healing and reducing wound-associated ulceration, particularly in the cornea and potentially in the skin of DM patients. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is one of the most prevalent diseases globally, and its prevalence is rapidly increasing. Most patients with a long-term history of DM present with some degree of keratopathy (DK). Despite its high incidence, the underlying inflammatory mechanism of DK has not been elucidated yet. For further insights into the underlying immunopathologic processes, we utilized streptozotocin-induced mice to model type 1 DM (T1D) and B6.Cg-Lepob/J mice to model type 2 DM (T2D). We evaluated the animals for the development of clinical manifestations of DK. Four weeks post-induction, the total frequencies of corneal CD45+CD11b+Ly-6G− myeloid cells, with enhanced gene and protein expression levels for the proinflammatory cytokines TNF-α and IL-1β, were higher in both T1D and T2D animals. Additionally, the frequencies of myeloid cells/mm2 in the sub-basal neural plexus (SBNP) were significantly higher in T1D and T2D compared to non-diabetic mice. DK clinical manifestations were observed four weeks post-induction, including significantly lower tear production, corneal sensitivity, and epitheliopathy. Nerve density in the SBNP and intraepithelial terminal endings per 40x field were lower in both models compared to the normal controls. The findings of this study indicate that DM alters the immune quiescent state of the cornea during disease onset, which may be associated with the progressive development of the clinical manifestations of DK.

Diabetic keratopathy (DK) is a common ocular complication of diabetes, characterized by alteration of the normal wound-healing mechanism, reduction of epithelial hemidesmosomes, disruption of the basement membrane, impaired barrier function, reduced corneal sensitivity, corneal ulcers, and corneal edema. The limited number of clinical studies do not allow a full characterization of the pathophysiology of DK and, until now, effective therapeutic approaches have not been available. However, in recent years, neuropeptides gained great attention for their biochemical characteristics and therapeutic potential. This review focuses on the role of neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the eye and, in particular, in the cornea, in physiological conditions, or during DK, by providing an overview of this diabetes mellitus complication.

Purpose: Oxidative stress and inflammation had been proved to play important role in the progression of diabetic keratopathy (DK). The excessive accumulation of AGEs and their bond to AGE receptor (RAGE) in corneas that cause the formation of oxygen radicals and the release of inflammatory cytokines, induce cell apoptosis. Our current study was aimed to evaluate the effect of ALA on AGEs accumulation as well as to study the molecular mechanism of ALA against AGE-RAGE axis mediated oxidative stress, apoptosis, and inflammation in HG-induced HCECs, so as to provide cytological basis for the treatment of DK. Methods: HCECs were cultured in a variety concentration of glucose medium (5.5, 10, 25, 30, 40, and 50 mM) for 48 h. The cell proliferation was evaluated by CCK-8 assay. Apoptosis was investigated with the Annexin V- fluorescein isothiocyanate (V-FITC)/PI kit, while, the apoptotic cells were determined by flow cytometer and TUNEL cells apoptosis Kit. According to the results of cell proliferation and cell apoptosis, 25 mM glucose medium was used in the following HG experiment. The effect of ALA on HG-induced HCECs was evaluated. The HCECs were treated with 5.5 mM glucose (normal glucose group, NG group), 5.5 mM glucose + 22.5 mM mannitol (osmotic pressure control group, OP group), 25 mM glucose (high glucose group, HG group) and 25 mM glucose + ALA (HG + ALA group) for 24 and 48 h. The accumulation of intracellular AGEs was detected by ELISA kit. The RAGE, catalase (CAT), superoxide dismutase 2 (SOD2), cleaved cysteine-aspartic acid protease-3 (Cleaved caspase-3), Toll-like receptors 4 (TLR4), Nod-like receptor protein 3 (NLRP3) inflammasome, interleukin 1 beta (IL-1 ß), and interleukin 18 (IL-18) were quantified by RT-PCR, Western blotting, and Immunofluorescence, respectively. Reactive oxygen species (ROS) production was evaluated by fluorescence microscope and fluorescence microplate reader. Results: When the glucose medium was higher than 25 mM, cell proliferation was significantly inhibited and apoptosis ratio was increased (P < 0.001). In HG environment, ALA treatment alleviated the inhibition of HCECs in a dose-dependent manner, 25 μM ALA was the minimum effective dose. ALA could significantly reduce the intracellular accumulation of AGEs (P < 0.001), activate protein and genes expression of CAT and SOD2 (P < 0.001), and therefore inhibited ROS-induced oxidative stress and cells apoptosis. Besides, ALA could effectively down-regulate the protein and gene level of RAGE, TLR4, NLRP3, IL-1B, IL-18 (P < 0.05), and therefore alleviated AGEs-RAGE-TLR4-NLRP3 pathway–induced inflammation in HG-induced HCECs. Conclusion: Our study indicated that ALA could be a desired treatment for DK due to its potential capacity of reducing accumulation of advanced glycation end products (AGEs) and down-regulating AGE-RAGE axis–mediated oxidative stress, cell apoptosis, and inflammation in high glucose (HG)–induced human corneal epithelial cells (HCECs), which may provide cytological basis for therapeutic targets that are ultimately of clinical benefit. [ABSTRACT FROM AUTHOR]

Continuous replenishment of the corneal epithelium is pivotal for maintaining optical transparency and achieving optimal visual perception. This dynamic process is driven by limbal epithelial stem cells (LESCs) located at the junction between the cornea and conjunctiva, which is otherwise known as the limbus. In patients afflicted with diabetes, hyperglycemia-induced impairments in corneal epithelial regeneration results in persistent epithelial and other defects on the ocular surface, termed diabetic keratopathy (DK), which progressively diminish vision and quality of life. Reports of delayed corneal wound healing and the reduced expression of putative stem cell markers in diabetic relative to healthy eyes suggest that the pathogenesis of DK may be associated with the abnormal activity of LESCs. However, the precise role of these cells in diabetic corneal disease is poorly understood and yet to be comprehensively explored. Herein, we review existing literature highlighting aberrant LESC activity in diabetes, focusing on factors that influence their form and function, and emerging therapies to correct these defects. The consequences of malfunctioning or depleted LESC stocks in DK and limbal stem cell deficiency (LSCD) are also discussed. These insights could be exploited to identify novel targets for improving the management of ocular surface complications that manifest in patients with diabetes.

It is estimated that currently, about 46%-64% of patients with diabetes mellitus(DM)suffer from diabetic keratopathy(DK). With the increasing prevalence of DM, DK has gradually been concerned by ophthalmologists. Nevertheless, its pathogenesis is not yet clear. Oxidative stress is a pathological process that causes excessive production of reactive oxygen species(ROS)and reactive nitrogen species(RNS)in the body, which damages tissues and cells. It participates in the occurrence and development of many diseases, including the ocular complications of DM. This study aims to review the research progress of oxidative stress in the pathogenesis and the treatment of diabetic corneal lesions, thus providing references for clinical diagnosis and treatment of DK.

Background: Diabetic keratopathy is a prevalent but sometimes ignored visual condition in diabetic patients, which significantly affects patients with diabetes mellitus (DM) in terms of their visual acuity. Exosomes regulate diabetes-related conditions like diabetic keratopathy (DK) by secreting their components into the body., Objective: Aim to investigate the effect and mechanism of mesenchymal stem cell (MSC)-derived exosome miR-125a-5p on DK., Methods: Transmission electron microscopy, along with nanoparticle tracking analysis, was used to determine the morphology and size of exosomes. To evaluate cell viability, proliferation, and migration, Western blotting and RT-qPCR methods were used. CCK-8, cell cloning, and scratch assays were used to measure protein levels and mRNA expression., Results: High glucose treatment of corneal epithelial cells weakened cell viability, proliferation and migration, and the level of miR-125a-5p was significantly reduced. It has been proposed that elevated levels of miR-125a-5p could enhance cell viability, proliferation, and migration, can inhibit endoplasmic reticulum stress induced by high glucose, which is the same as the effect of endoplasmic reticulum stress inhibitors., Conclusion: Mouse bone marrow MSC-derived exosome miR-125a-5p repairs corneal epithelial cell viability and proliferation as well as migration ability to improve DK by inhibiting high glucose-induced endoplasmic reticulum stress., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare that are relevant to the content of this article., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

With the global prevalence of diabetes mellitus over recent decades, more patients suffered from various diabetic complications, including diabetic ocular surface diseases that may seriously affect the quality of life and even vision sight. The major diabetic ocular surface diseases include diabetic keratopathy and dry eye. Diabetic keratopathy is characterized with the delayed corneal epithelial wound healing, reduced corneal nerve density, decreased corneal sensation and feeling of burning or dryness. Diabetic dry eye is manifested as the reduction of tear secretion accompanied with the ocular discomfort. The early clinical symptoms include dry eye and corneal nerve degeneration, suggesting the early diagnosis should be focused on the examination of confocal microscopy and dry eye symptoms. The pathogenesis of diabetic keratopathy involves the accumulation of advanced glycation end-products, impaired neurotrophic innervations and limbal stem cell function, and dysregulated growth factor signaling, and inflammation alterations. Diabetic dry eye may be associated with the abnormal mitochondrial metabolism of lacrimal gland caused by the overactivation of sympathetic nervous system. Considering the important roles of the dense innervations in the homeostatic maintenance of cornea and lacrimal gland, further studies on the neuroepithelial and neuroimmune interactions will reveal the predominant pathogenic mechanisms and develop the targeting intervention strategies of diabetic ocular surface complications.

Objective: This study investigated the effects of acute angle closure crisis (AACC) on the corneal endothelial cells in patients with type 2 diabetes mellitus (DM) to identify the factors that cause corneal endothelial cell injury. Methods: We examined 154 patients who visited Qingdao Eye Hospital for AACC in one eye (154 eyes; 28 men and 126 women; mean age of 68 ± 8 years). We divided the participants into non-DM, DM well-control, and DM poorcontrol groups, with the unaffected eyes used as controls. Each participant was evaluated at the hospital while under AACC. We measured the relevant index and corneal parameters of the participants for statistical analysis. Results: There were significant statistical differences in corneal parameters among the three groups. The decreased levels of central endothelial cell density (CD) and the percentage of hexagonal cells (6A) were statistically relevant among the groups (P<0.05). The AACC duration was correlated with CD loss rate among the groups (P<0.05). The DM duration was correlated with CD loss rate in the DM well-control group. Compared with the non-DM group, the level of 6A decreased more significantly in the DM group after AACC (P<0.05). The AACC duration in the DM well-control group was significantly shorter than in the non-DM and DM poor-control groups (P<0.001). The DM poor-control group showed significantly worse visual acuity when compared with the other groups (P<0.05). Conclusions: DM may impact the functional status of corneal endothelial cells. AACC can worsen the corneal endothelium damage in patients with DM. Blood glucose levels and the duration of intraocular hypertension are closely related to the severity of corneal endothelial injury. [ABSTRACT FROM AUTHOR]

The IL-36 cytokines are known to play various roles in mediating the immune and inflammatory response to tissue injury in a context-dependent manner. This study investigated the role of IL-36R signaling in mediating epithelial wound healing in normal (NL) and diabetic (DM) C57BL/6 mouse corneas. The rate of epithelial wound closure was significantly accelerated in IL-36 receptor-deficient (IL-36R−/−) compared to wild-type (WT) mice. Wounding increased IL-36α and -36γ but repressed IL-36R antagonist (IL-36Ra) expression in B6 mouse corneal epithelial cells. The wound-induced proinflammatory cytokines CXCL1 and CXCL2 were dampened, while the antimicrobial peptides (AMPs) S100A8 and A9 were augmented in IL-36R−/− mouse corneas. Intriguingly, the expression of AMP LCN2 was augmented at the mRNA level. LCN2 deficiency resulted in an acceleration of epithelial wound healing. IL-36R deficiency also greatly increased the healing rate of the corneal epithelial wound in DM mice. IL-36R deficiency also suppressed IL-1β, IL-1Ra, and ICAM expression in unwounded-DM mice and wounded NL corneas. Opposing IL-1β and ICAM, the expression of IL-Ra in DM corneas of IL-36R−/− mice was augmented. The presence of recombinant IL-1Ra and IL-36Ra accelerated epithelial wound closure in T1DM corneas of B6 mice. Our study revealed an unprecedented role of IL-36R signaling in controlling corneal epithelial wound healing in normal (NL) and diabetic (DM) mice. Our data suggest that IL-36Ra, similar to IL-1Ra, might be a therapeutic reagent for improving wound healing and reducing wound-associated ulceration, particularly in the cornea and potentially in the skin of DM patients.

Aim: To formulate a novel nano-phytochemical ophthalmic solution to promote corneal wound healing. Methods: Dipotassium glycyrrhizinate (DG) and palmatine (PAL) were used to formulate this formulation marked as DG–PAL, and its efficacy and mechanisms for promoting corneal wound healing were evaluated in mice. Results: DG–PAL was easily fabricated with excellent physical profiles. In in vivo efficiency evaluations, DG–PAL demonstrated an excellent promoting effect on corneal epithelial/nerve wound healing in both healthy and diabetic mice. These effects were involved in the DG–PAL-induced decreased expression levels of HMGB1 and its signaling-related factors in the corneas and trigeminal neurons of the healthy or diabetic mice. Conclusion: DG–PAL possibly represents a promising ophthalmic solution for promoting corneal wound healing. [ABSTRACT FROM AUTHOR]

Atsuyoshi Dota, Asuka Sakamoto, Takashi Nagano, Tadahiro Murakami, Takeshi Matsugi Nara Research & Development Center, Santen Pharmaceutical Co., Ltd, Ikoma-shi, Nara, JapanCorrespondence: Atsuyoshi DotaNara Research & Development Center, Santen Pharmaceutical Co., Ltd., 8916-16 Ikoma-shi, Nara 630-0101, JapanTel +81 743 79 4525Fax +81 743 79 4591Email atsuyoshi.dota@santen.comPurpose: To examine the effect of 3% diquafosol ophthalmic solution (DQS) on ocular surface disorders in diabetic model rats maintained in a continuous airflow condition.Methods: Goto–Kakizaki (GK) rats, a spontaneous model of type 2 diabetes, were exposed to constant airflow for 8 weeks. After the establishment of the animal model in this environment, DQS or saline was instilled six times a day into GK rat eyes for 6 weeks. Schirmer’s test was performed before and after 6-week instillations. Corneal fluorescein staining was scored at 2-, 4-, and 6-week instillations. Touch thresholds for the cornea were also determined using a Cochet–Bonnet esthesiometer before and after 6-week instillations.Results: The mean Schirmer’s test score after instillation of DQS was twice higher than that recorded for saline alone. DQS significantly decreased corneal staining scores at 4- and 6-week instillations. No changes in touch thresholds were observed before and after 6-week instillations.Conclusion: These results suggest that DQS improves corneal epithelial damage by stimulating tear secretion without influencing corneal sensation in diabetic keratopathy. Thus, DQS may have potential for treatment of diabetic patients with dry eye.Keywords: diquafosol ophthalmic solution, corneal epithelial damage, tear volume, diabetic keratopathy, Goto–Kakizaki rat

Diabetes mellitus (DM) is a complex metabolic disorder. Long-term hyperglycemia may induce diabetic keratopathy (DK), which is mainly characterized by delayed corneal epithelial regeneration. MicroRNAs (miRNAs) have been reported to play regulatory roles during tissue regeneration. However, the molecular mechanism by which miRNAs influence epithelial regeneration in DK is largely unknown. In this study, we performed miRNA and mRNA sequencing of regenerative corneal epithelium tissue from streptozotocin-induced type 1 diabetic (T1DM) and wild-type mice to screen for differentially expressed miRNAs and mRNAs. Based on regulatory network analysis, miR-223-5p was selected for subsequent experiments and Hpgds was then identified as a direct target gene. MiR-223-5p downregulation significantly promoted diabetic corneal epithelial wound healing and nerve regeneration. However, the beneficial effects of miR-223-5p inhibition were abolished by an Hpgds inhibitor. Furthermore, mechanistic studies demonstrated that miR-223-5p suppression ameliorated inflammation and enhanced cell proliferation signaling in DK. Taken together, our findings revealed that the regulatory role of miR-223-5p in diabetic corneal epithelial and nerve regeneration by mediating inflammatory processes and cell proliferation signaling. And silencing miR-223-5p may contribute to the development of potential therapeutic strategies for DK.

The incidence of diabetes mellitus (DM) and its complications have increased considerably worldwide. Diabetic keratopathy is the major complication of the cornea characterized by delayed corneal wound healing, decreasing corneal epithelial sensitivity, and recurrent corneal ulcers. There is accumulating evidence that diabetic keratopathy is correlated with the hyperglycemic state. Different corneal components may produce different alterations under hyperglycemia. In addition, diabetic nerve alteration may become a novel biomarker of early-stage DM. Abnormalities of the corneal nerve plexus have been associated with diabetic inflammatory states. There is rapidly growing evidence based on investigations of diabetic corneal nerves through in vivo confocal microscopy. Understanding the molecular pathogenesis caused by hyperglycemia may assist in the identification of novel biomarkers, as well as therapeutic targets for early treatment. This review mainly summarizes recent findings on corneal alteration and pathogenesis in DM.

Various etiologies, including diabetic keratopathy (DK), dry eye disease (DED), and neurotrophic keratopathy (NK), can disrupt corneal homeostasis, exacerbating corneal epithelial defects. Topical insulin has emerged as a promising therapy for promoting corneal wound healing and addressing underlying pathologies. This review systematically evaluates the efficacy of topical insulin across different corneal disorders. A literature review was conducted across the PubMed, Google Scholar, and Scopus research databases. The search resulted in a total of 19 articles, consisting of clinical trials, retrospective studies, and case reports. In DK, topical insulin accelerates corneal wound healing post-vitreoretinal surgery with lower concentrations showing higher outcomes when compared to conventional therapy, possibly due to improved epithelial stem cell migration. In comparison, the dry-eye disease results are inconclusive regarding patient-reported outcomes and corneal staining. For NK, topical insulin accelerates corneal wound healing and restores corneal nerve sensation. Other persistent epithelial defect (PED) etiologies that have been treated with topical insulin are infection, immune-mediated, mechanical and chemical trauma, and chronic ocular surface alterations. Although individual mechanisms for the benefits of topical insulin for each of these etiologies have not been studied, the literature demonstrates that topical insulin is efficacious for PEDs regardless of etiology. Future clinical trials need to be conducted to further evaluate optimal dosing, duration, and use of topical insulin for the restoration of the corneal surface., Competing Interests: Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Moin et al.)

Background: To develop a strategy based on surgical removal of a degenerated corneal epithelial scaffold for treatment of persistent epithelial defects (PEDs) in diabetic keratopathy. Case Presentation: Three diabetic patients with PEDs were initially treated with eyedrops containing the fibronectin-based peptide PHSRN (Pro-His-Ser-Arg-Asn) or both the substance P-derived peptide FGLM-NH2 and the insulin-like growth factor-1-derived peptide SSSR. A degenerated Bowman’s layer or calcified lesion thought to be responsible for incomplete healing was surgically removed after confirmation of reactivity to the peptide eyedrops. All three patients achieved complete epithelial wound closure after surgery. Two cases treated by phototherapeutic keratectomy or lamellar keratoplasty did not show PED recurrence during 6 or 36 months of follow-up, respectively. One case treated by mechanical removal of a degenerated Bowman’s layer manifested recurrence after 1 month, but resurfacing of the defect was again achieved after repeat surgery. Conclusion: We propose a new strategy for treatment of diabetic PEDs based on surgical remodeling of the corneal epithelial scaffold for patients who respond to peptide eyedrops but fail to achieve wound closure.

Ocular complications from diabetes mellitus are common. Diabetic keratopathy, the most frequent clinical condition affecting the human cornea, is a potentially sight-threatening condition caused mostly by epithelial disturbances that are of clinical and research attention because of their severity. Diabetic keratopathy exhibits several clinical manifestations, including persistent corneal epithelial erosion, superficial punctate keratopathy, delayed epithelial regeneration, and decreased corneal sensitivity, that may lead to compromised visual acuity or permanent vision loss. The limited amount of clinical studies makes it difficult to fully understand the pathobiology of diabetic keratopathy. Effective therapeutic approaches are elusive. We summarize the clinical manifestations of diabetic keratopathy and discuss available treatments and up-to-date research studies in an attempt to provide a thorough overview of the disorder. [ABSTRACT FROM AUTHOR]

Corneal dysfunctions associated with Diabetes Mellitus (DM), termed diabetic keratopathy (DK), can cause impaired vision and/or blindness. Hypoxia affects both Type 1 (T1DM) and Type 2 (T2DM) surprisingly, the role of hypoxia in DK is unexplored. The aim of this study was to examine the impact of hypoxia in vitro on primary human corneal stromal cells derived from Healthy (HCFs), and diabetic (T1DMs and T2DMs) subjects, by exposing them to normoxic (21% O 2) or hypoxic (2% O 2) conditions through 2D and 3D in vitro models. Our data revealed that hypoxia affected T2DMs by slowing their wound healing capacity, leading to significant alterations in oxidative stress-related markers, mitochondrial health, cellular homeostasis, and endoplasmic reticulum health (ER) along with fibrotic development. In T1DMs, hypoxia significantly modulated markers related to membrane permeabilization, oxidative stress via apoptotic marker (BAX), and protein degradation. Hypoxic environment induced oxidative stress (NOQ1 mediated reduction of superoxide in T1DMs and Nrf2 mediated oxidative stress in T2DMs), modulation in mitochondrial health (Heat shock protein 27 (HSP27), and dysregulation of cellular homeostasis (HSP90) in both T1DMs and T2DMs. This data underscores the significant impact of hypoxia on the diabetic cornea. Further studies are warranted to delineate the complex interactions. • Hypoxia significantly influenced T2DMs by slowing their wound healing capacity. • Hypoxic T1DMs and T2DMs modulated HSP27 and HSP90 expressions. • Hypoxia lead to oxidative stress in T1DMs via SOD1, SOD2, and BAX downregulation. [ABSTRACT FROM AUTHOR]

AIM: To observe the effect of two kinds of bandage contact lenses on epithelial erosions and corneal thickness after vitreoretinal surgery for proliferative diabetic retinopathy(PDR). METHODS: In this prospective, nonrandomized, comparative clinical study, 69 eyes of 69 patients with PDR were divided into two groups. They underwent vitreoretinal surgery. Group A, 36 eyes of 36 cases, the bandage contact lens with diameter of 13.8mm were covered on corneal surface during surgery under noncontact wide-angle viewing systems. Group B, 33 eyes of 33 cases, the bandage contact lens with diameter of 14.0mm were covered on corneal surface during the same surgery. Visual acuity, intraocular pressure, slit-lamp examination, corneal fluorescein sodium staining, count of corneal endothelium cells, measure of corneal thickness before and after operation were assessed.RESULTS: Pre-operation, corneal fluorescein sodium staining positive rate was 42% in Group A and 42% in Group B(χ2=0.004, P=0.949). At 1d after surgery, the positive rate of was 47% in Group A and 45% in Group B(χ2=0.022, P=0.883). At 2d after surgery, the positive rate of was 44% in Group A and 45% in Group B(χ2=0.007, P=0.933). At 3d after surgery, the positive rate of was 44% in Group A and 42% in Group B(χ2=0.029, P=0.886). At 7d after surgery, the positive rate of was 42% in Group A and 39% in Group B(χ2=0.037, P=0.848). Count of corneal endothelium cells showed no significant difference between Group A and Group B(P>0.05). Count of corneal endothelium cells of Group A before surgery and at 7d after surgery were 2779.25±329.55 /mm2, 2777.14±331.17 /mm2, without significant difference(t=0.551, P=0.585); those of Group B were 2678.61±335.64/mm2, 2672.45±336.25 /mm2, without significant difference(t=1.774, P=0.086). Measure of corneal thickness was 519.25±23.42μm before surgery and 542.03±25.94μm after surgery in Group A(t=-6.854, Pt=-7.204, PCONCLUSION: Two kinds of bandage contact lenses are used in vitreoretinal surgery in diabetic patients. The corneal epithelial integrity shows no difference before and after surgery. Both the bandage contact lens could protect the corneal epithelium and maintain good corneal transparency during vitreoretinal surgery.

Ocular diseases cause visual impairment and blindness, imposing a devastating impact on quality of life and a substantial societal economic burden. Many such diseases lack universally effective pharmacotherapies. Therefore, understanding the mediators involved in their pathophysiology is necessary for the development of therapeutic strategies. To this end, the hydrolase activity of soluble epoxide hydrolase (sEH) has been explored in the context of several eye diseases, due to its implications in vascular diseases through metabolism of bioactive epoxygenated fatty acids. In this mini-review, we discuss the mounting evidence associating sEH with ocular diseases and its therapeutic value as a target. Substantial data link sEH with the retinal and choroidal neovascularization underlying diseases such as wet age-related macular degeneration, retinopathy of prematurity, and proliferative diabetic retinopathy, although some conflicting results pose challenges for the synthesis of a common mechanism. sEH also shows therapeutic relevance in non-proliferative diabetic retinopathy and diabetic keratopathy, and sEH inhibition has been tested in a uveitis model. Various approaches have been implemented to assess sEH function in the eye, including expression analyses, genetic manipulation, pharmacological targeting of sEH, and modulation of certain lipid metabolites that are upstream and downstream of sEH. On balance, sEH inhibition shows considerable promise for treating multiple eye diseases. The possibility of local delivery of inhibitors makes the eye an appealing target for future sEH drug development initiatives.

Abstract We aim to investigate how Sirt3 (silent mating type information regulation 2 homolog 3) promoting diabetic corneal epithelial wound healing by regulating mitophagy. The effect of HG(High Glucose, 25 mM D-glucose) on Sirt3 and LC3B(light chain 3 beta)which representing of mitophagy were investigated in TKE2 cells (a murine limbal/corneal epithelium-derived progenitor cell line) and corneal epithelium from C57BL/6J-Ins2Akita (Ins2Akita/+) mice using RT-PCR and Western blotting. How overexpression of Sirt3 promoting diabetic corneal epithelial wound healing was investigated with cell migration assay、immunofluorescence、 immunofluorescence colocalization and corneal injury model. We found that HG reduced the expression of Sirt3 as well the mitophagy both in TKE2 cells and corneas from Ins2Akita/+ mice. And overexpression of Sirt3 prominently promoted wound healing speed under HG condition via upregulating the level of mitophagy. Mitophagy level was increased dramatically when the Foxo3a (Forkhead box O3)/PINK1(PTEN Induced putative kinase protein 1)-Parkin pathway was activated by Sirt3 overexpression which suggested that the mitophagy was involved in cell injury under HG condition. This study demonstrated the mechanism of Sirt3 regulating mitophagy to promote diabetic corneal epithelial wound healing in vivo and in vitro, which suggested that Sirt3 may positively impact diabetic keratopathy(DK). Highlights • High glucose conditions inhibate the expression of Sirt3 in the TKE2 cells and corneal epithelia of type 1 diabetic mice. • The activation of mitophagy is downregulated by Sirt3 under HG conditions. • Sirt3 regulates mitophagy to promote diabetic corneal epithelial wound healing via the Foxo3a/PINK1-Parkin Pathway. [ABSTRACT FROM AUTHOR]

Ocular diseases cause visual impairment and blindness, imposing a devastating impact on quality of life and a substantial societal economic burden. Many such diseases lack universally effective pharmacotherapies. Therefore, understanding the mediators involved in their pathophysiology is necessary for the development of therapeutic strategies. To this end, the hydrolase activity of soluble epoxide hydrolase (sEH) has been explored in the context of several eye diseases, due to its implications in vascular diseases through metabolism of bioactive epoxygenated fatty acids. In this mini-review, we discuss the mounting evidence associating sEH with ocular diseases and its therapeutic value as a target. Substantial data link sEH with the retinal and choroidal neovascularization underlying diseases such as wet age-related macular degeneration, retinopathy of prematurity, and proliferative diabetic retinopathy, although some conflicting results pose challenges for the synthesis of a common mechanism. sEH also shows therapeutic relevance in non-proliferative diabetic retinopathy and diabetic keratopathy, and sEH inhibition has been tested in a uveitis model. Various approaches have been implemented to assess sEH function in the eye, including expression analyses, genetic manipulation, pharmacological targeting of sEH, and modulation of certain lipid metabolites that are upstream and downstream of sEH. On balance, sEH inhibition shows considerable promise for treating multiple eye diseases. The possibility of local delivery of inhibitors makes the eye an appealing target for future sEH drug development initiatives. [ABSTRACT FROM AUTHOR]

Diabetic keratopathy (DK) is the major complication of the cornea characterizing diabetes-affected patients. This ocular pathology is correlated with the hyperglycemic state leading to delayed corneal wound healing and recurrent corneal ulcers. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with widespread distribution throughout the body, and exerting cytoprotective effects in the neural and non-neuronal parts of the eye, including the cornea. The purpose of the present study was to investigate whether changes in PACAP expression can concur for delayed epithelial wound healing in diabetic cornea and whether the protective effect of the peptide could be mediated through the activation of the EGFR signaling pathway, which has been reported to be impaired in DK. Expression and distribution of PACAP, PAC1R, and EGFR were investigated through immunohistochemistry analysis in the cornea of normal and diabetic rats. The role of the peptide on wound healing during DK was evaluated in an in vitro model represented by rabbit corneal epithelial cells grown in high glucose conditions. Western blotting and immunofluorescence analysis were used to examine the ability of PACAP to induce the activation of the EGFR/ERK1/2 signaling pathway. Our results showed that in diabetic cornea the expression of PACAP, PAC1R, and EGFR is drastically reduced. The treatment with PACAP via PAC1R activation enhanced cell viability and corneal epithelium wound healing in cells grown under high glucose conditions. Furthermore, both EGFR and ERK1/2 signaling was induced upon the peptide treatment. Overall, our results showed the trophic efficiency of PACAP for enhancing the corneal epithelium re-epithelialization suggesting that the peptide could be beneficially valuable as a treatment for DK. • In diabetic cornea the endogenous expression of PACAP, PAC1R, and EGFR is drastically reduced. • PACAP via PAC1R activation promoted cell viability and wound healing in corneal epithelial cells grown under high glucose. • PACAP enhanced corneal epithelium re-epithelialization through EGFR and ERK1/2 signaling activation. [ABSTRACT FROM AUTHOR]

Background: To develop a strategy based on surgical removal of a degenerated corneal epithelial scaffold for treatment of persistent epithelial defects (PEDs) in diabetic keratopathy. Case Presentation: Three diabetic patients with PEDs were initially treated with eyedrops containing the fibronectin-based peptide PHSRN (Pro-His-Ser-Arg-Asn) or both the substance P-derived peptide FGLM-NH2 and the insulin-like growth factor-1-derived peptide SSSR. A degenerated Bowman's layer or calcified lesion thought to be responsible for incomplete healing was surgically removed after confirmation of reactivity to the peptide eyedrops. All three patients achieved complete epithelial wound closure after surgery. Two cases treated by phototherapeutic keratectomy or lamellar keratoplasty did not show PED recurrence during 6 or 36 months of follow-up, respectively. One case treated by mechanical removal of a degenerated Bowman's layer manifested recurrence after 1 month, but resurfacing of the defect was again achieved after repeat surgery. Conclusion: We propose a new strategy for treatment of diabetic PEDs based on surgical remodeling of the corneal epithelial scaffold for patients who respond to peptide eyedrops but fail to achieve wound closure. [ABSTRACT FROM AUTHOR]

Most treatments for diabetic eye conditions rely on systemic (oral) or intravitreal administration, and there is still a demand of efficient and comfortable ocular dosage forms. Our purpose was to design contact lenses (CLs) suitable for local prophylaxis/treatment of diabetes-related ocular pathologies, by means of the incorporation of bioinspired functional groups that can reversibly interact with epalrestat, an aldose reductase inhibitor. Several sets of silicone hydrogels were synthesized varying the contents in 2-hydroxyethyl methacrylate (HEMA), monomethacryloxypropyl-sym-polydimethylsiloxane hydroxypropyl terminated (MCS-MC12), and aminopropyl methacrylamide (APMA). Epalrestat was incorporated before or after polymerization, and loading and release profiles compared. All sets were evaluated regarding optical properties, oxygen permeability, swelling, cytocompatibility, ocular irritation, and corneal drug penetration (using a drug solution as reference). Designed silicone hydrogels showed adequate properties to be used as CLs. Affinity for epalrestat strongly depended on the content in APMA, which endowed the hydrogels with prolonged release in 0.9% NaCl for one week, both after synthesis and after being re-loaded. Bovine corneal permeability tests demonstrated that epalrestat released from the hydrogels can efficiently accumulate into the cornea in spite the concentrations provided on cornea surface were lower than those attained after instillation of concentrated eyedrops. Epalrestat-loaded hydrogels also demonstrated anti-cataract activity in an in vitro model of diabetic eye. Overall, silicone hydrogel CLs functionalized with bioinspired chemical groups represent a first attempt to design CLs adapted to the needs of diabetic eyes, acting as controlled release platforms of epalrestat, promoting drug accumulation and diffusion through cornea. [ABSTRACT FROM AUTHOR]

Diabetic keratopathy (DK) is a common ocular complication of diabetes in which the dendritic cells (DCs)-mediated inflammatory response plays an important role. Nerve growth factor (NGF)/Tropomyosin receptor kinase A (TrkA)-mediated inhibition of the nuclear factor kappa B (NF-κB) pathway can reduce inflammatory cytokine production. Extracellular vesicles (EVs) derived from mouse adipose-derived mesenchymal stem cells (mADSC-EVs) have been explored extensively as treatments for degenerative eye disease. However, mADSC-EVs is poorly studied in the DK models. In this study, we investigated the anti-inflammatory effects of mADSC-EVs and explored the underlying mechanisms in vitro and in vivo DK models. Our results showed that mADSC-EVs have significant therapeutic effects including increasing tear volume and the ratio of lacrimal gland/body weight, promoting corneal nerve regeneration, and sensation recovery in streptozotocin (STZ)-induced DK mice. In addition, mADSC-EVs significantly reduced the inflammatory response involving DCs, consistently up-regulated protein expression of the NGF/TrkA pathway, and importantly, reduced lipopolysaccharide (LPS)-mediated IL-6 and TNF-α expression and directly dependent on TrkA in the induced culture of bone marrow-derived DCs (BMDCs). Taken together, our findings revealed that mADSC-EVs promoted diabetic corneal epithelial wound healing through NGF/TrkA pathway activation involving DCs. Given the significant therapeutic efficacy of mADSC-EVs and its clinical application, mADSC-EVs appears to be a promising new therapy for DK. • mADSCs-Exos promoted corneal epithelial wound healing and nerve regeneration in DK mice. • mADSC-Exos inhibited the release of pro-inflammatory cytokines from mature corneal DCs. • mADSC-Exos activated NGF/TrkA pathway in DCs. • Exosomes may serve as novel therapeutic tools for DK in the future. [ABSTRACT FROM AUTHOR]

Diabetic keratopathy (DK), the diabetic complication in the cornea, is characterized by the delayed epithelial regeneration and sensory nerve degeneration. The involvement of limbal stem/progenitor cells (LSPCs) dysfunction has been reported, however the pathogenic mechanisms remain unclear. Here, we confirmed the dysfunction of LSPCs in diabetic mouse and human corneas. The sympathetic nerve in the cornea was adjacent to LSPCs, and the sympathetic overactivation was found in diabetic mice. Surgical and pharmacological ablation of sympathetic nerves rescued the LSPCs function and promoted corneal epithelial regeneration in diabetic mice. In contrast, both topical norepinephrine (NE) application and chemogenetic sympathetic overactivation directly impaired the stemness and proliferation characteristics of LSPCs, as well as the normal epithelial regeneration. Moreover, we identified that β2-adrenoceptor (Adrb2) was the predominant adrenergic receptor expressed in LSPCs by corneal limbal single-cell sequencing and real time PCR (RT-PCR) analysis of sorted LSPCs. The Adrb2 knockout mice exhibited the enhancement of epithelial regeneration and LSPCs function, compared with the wild-type mice. Similarly, topical application of the Adrb2 specific antagonist ICI 118, 551 effectively accelerated diabetic corneal epithelial regeneration with the restored LSPCs function. Mechanistically, sonic hedgehog (Shh) activity mediated the downstream effects of NE-Adrb2 signaling pathway in regulating LSPCs and epithelial regeneration. Taken together, our data revealed the involvement of sympathetic overactivation in the impairment of diabetic LSPCs function and corneal epithelial regeneration through the NE-Adrb2-Shh signaling pathway. The interference of sympathetic overactivation may provide novel treatment strategies for diabetic keratopathy. [Display omitted] • Hyperglycemia impairs the function of LSPCs. • Hyperglycemia induces sympathetic overactivation. • Sympathetic nerve suppression enhances LSPCs function through NE-Adrb2. • NE-Adrb2 mediated the function of LSPCs by inhibiting Shh pathway. [ABSTRACT FROM AUTHOR]