Exorbital Lacrimal Gland Ablation and Regrafting Induce Inflammation but Not Regeneration or Dry Eye.

The study evaluated the regenerative responses of the lacrimal functional unit (LFU) after lacrimal gland (LG) ablation. The LG of Wistar rats was submitted to G1) partial LG ablation, G2) partial ablation and transplantation of an allogeneic LG, or G3) total LG ablation, (n = 7-10/group). The eye wipe test, slit lamp image, tear flow, and histology were evaluated. RT-PCR analyzed inflammatory and proliferation mediators. The findings were compared to naïve controls after 1 and 2 months (M1 and M2). G3 presented increased corneal sensitivity, and the 3 groups showed corneal neovascularization. Histology revealed changes in the LG and corneal inflammation. In the LG, there was an increase in MMP-9 mRNA of G1 and G2 at M1 and M2, in RUNX-1 at M1 and M2 in G1, in RUNX-3 mRNA at M1 in G1, and at M2 in G2. TNF-α mRNA rose in the corneas of G1 and G2 at M2. There was an increase in the IL-1ß mRNA in the trigeminal ganglion of G1 at M1. Without changes in tear flow or evidence of LG regeneration, LG ablation and grafting are unreliable models for dry eye or LG repair in rats. The surgical manipulation extended inflammation to the LFU.

Diquafosol Improves Corneal Wound Healing by Inducing NGF Expression in an Experimental Dry Eye Model.

Dry eye disease (DED) is caused by inflammation and damage to the corneal surface due to tear film instability and hyperosmolarity. Various eye drops are used to treat this condition. Each eye drop has different properties and mechanisms of action, so the appropriate drug should be used according to clinical phenotypes. This study aims to compare the therapeutic mechanisms of cyclosporine A (CsA) and diquafosol tetrasodium (DQS). An experimental in vivo/in vitro model of DED using hyperosmolarity showed decreased cell viability, inhibited wound healing, and corneal damage compared to controls. Treatment with cyclosporine or diquafosol restored cell viability and wound healing and reduced corneal damage by hyperosmolarity. The expression of the inflammation-related genes il-1ß, il-1α, and il-6 was reduced by cyclosporine and diquafosol, and the expression of Tnf-α, c1q, and il-17a was reduced by cyclosporine. Increased apoptosis in the DED model was confirmed by increased Bax and decreased Bcl-2 and Bcl-xl expression, but treatment with cyclosporine or diquafosol resulted in decreased apoptosis. Diquafosol increased NGF expression and translocation into the extracellular space. DED has different damage patterns depending on the progression of the lesion. Thus, depending on the type of lesion, eye drops should be selected according to the therapeutic target, focusing on repairing cellular damage when cellular repair is needed or reducing inflammation when inflammation is high and cellular damage is severe.

Multimodal Approach in Dry Eye Disease Combining In Vivo Confocal Microscopy and HLA-DR Expression.

Purpose: The purpose of this study was to determine the association between corneal images provided by in vivo confocal microscopy (IVCM) with clinical parameters and conjunctival expression of HLA-DR antigen in patients with dry eye disease (DED). Methods: Two hundred fourteen eyes of 214 patients with DED were analyzed, consisting of 2 groups of patients - 63 with autoimmune dry eye disease (AIDED) and 151 with non-autoimmune dry eye disease (NAIDED). Patients underwent a full clinical examination, including symptom screening, using the Ocular Surface Disease Index (OSDI) questionnaire, and objective analysis of DED signs by Schirmer's testing, tear break-up time (TBUT), Oxford's test, and IVCM corneal imaging. The IVCM scoring criteria were based on corneal sub-basal nerve density (ND), nerve morphology (NM), and inflammatory cell (IC) density. Quantification of conjunctival HLA-DR antigen was performed by flow cytometry. Results: The total IVCM score (T-IVCM) as well as the IVCM-IC subscore (sc) were positively correlated with HLA-DR levels with r = 0.3, P < 0.001 and r = 0.3, P < 0.01, respectively in the total population of patients with DED. The IVCM-NDsc was negatively correlated with TBUT in patients with AIDED (r = -0.2, P < 0.05) and with the Schirmer's test in patients with NAIDED (r = -0.24, P < 0.05). However, the IVCM-NMsc was positively correlated with the Oxford score only in patients with AIDED (r = 0.3, P < 0.05). Conclusions: The proposed IVCM scoring system showed significant correlations with clinical parameters along with conjunctival HLA-DR quantification in patients with DED. Translational Relevance: The IVCM grading score represents an interesting point of commonality among clinical parameters, imaging, and molecular investigation of the ocular surface.

Tear Fluid Progranulin as a Noninvasive Biomarker for the Monitoring of Corneal Innervation Changes in Patients With Type 2 Diabetes Mellitus.

Purpose: This study aimed to investigate the expression levels of progranulin (PGRN) in the tears of patients with diabetic retinopathy (DR) versus healthy controls. Additionally, we sought to explore the correlation between PGRN levels and the severity of ocular surface complications in patients with diabetes. Methods: In this prospective, single-visit, cross-sectional study, patients with DR (n = 48) and age-matched healthy controls (n = 22) were included and underwent dry eye examinations. Tear fluid was collected, and its components were analyzed using the Luminex assay. The subbasal nerve plexus of all participants was evaluated by in vivo confocal microscopy. Results: Patients with DR exhibited more severe dry eye symptoms, along with a reduction in nerve fiber density, length, and branch density within the subbasal nerve plexus, accompanied by an increase in the number of dendritic cells. Tear PGRN levels were also significantly lower in patients with diabetes than in normal controls, and the levels of some inflammatory factors (TNF-α, IL-6, and MMP-9) were higher in patients with DR. Remarkably, the PGRN level significantly correlated with nerve fiber density (R = 0.48, P < 0.001), nerve fiber length (R = 0.65, P < 0.001), and nerve branch density (R = 0.69, P < 0.001). Conclusions: Tear PGRN levels might reflect morphological changes in the corneal nerve plexus under diabetic conditions, suggesting that PGRN itself is a reliable indicator for predicting the advancement of neurotrophic keratopathy in patients with diabetes. Translational Relevance: PGRN insufficiency on the ocular surface under diabetic conditions was found to be closely associated with nerve impairment, providing a novel perspective to discover the pathogenesis of diabetic complications, which could help in developing innovative therapeutic strategies.

SPARC overexpression in allogeneic adipose-derived mesenchymal stem cells in dog dry eye model induced by benzalkonium chloride.

BACKGROUND: Nowadays, companion and working dogs hold significant social and economic importance. Dry eye, also known as dry keratoconjunctivitis (KCS), a common disease in ophthalmology, can readily impact a dog's working capacity and lead to economic losses. Although there are several medications available for this disease, all of them only improve the symptoms on the surface of the eye, and they are irritating and not easy to use for long periods of time. Adipose-derived mesenchymal stem cells (ADMSC) are promising candidates for tissue regeneration and disease treatment. However, long-term in vitro passaging leads to stemness loss of ADMSC. Here, we aimed to use ADMSC overexpressing Secreted Protein Acidic and Rich in Cysteine (SPARC) to treat 0.25% benzalkonium chloride-treated dogs with dry eye to verify its efficacy. For in vitro validation, we induced corneal epithelial cell (HCECs) damage using 1 µg/mL benzalkonium chloride. METHODS: Fifteen male crossbred dogs were randomly divided into five groups: normal, dry eye self-healing control, cyclosporine-treated, ADMSC-CMV-treated and ADMSC-OESPARC-treated. HCECs were divided into four groups: normal control group, untreated model group, ADMSC-CMV supernatant culture group and ADMSC-OESRARC supernatant culture group. RESULTS: SPARC-modified ADMSC had the most significant effect on canine ocular surface inflammation, corneal injury, and tear recovery, and the addition of ADMSC-OESPARC cell supernatant also had a salvage effect on HCECs cellular damage, such as cell viability and cell proliferation ability. Moreover, analysis of the co-transcriptome sequencing data showed that SPARC could promote corneal epithelial cell repair by enhancing the in vitro viability, migration and proliferation and immunosuppression of ADMSC. CONCLUSION: The in vitro cell test and in vivo model totally suggest that the combination of SPARC and ADMSC has a promising future in novel dry eye therapy.

Precise longitudinal monitoring of corneal change through in vivo confocal microscopy in a rat dry eye disease model.

Purpose: While lacrimal gland removal is commonly used in animal models to replicate dry eye disease, research into systematically monitoring dry eye disease's longitudinal pathological changes is limited. In vivo confocal microscopy (Heidelberg Retina Tomograph 3 with a Rostock Cornea Module, Heidelberg Engineering Inc., Franklin, MA) can non-invasively reveal corneal histopathological structures. To monitor dry-eye-disease-related changes in corneal structures, we developed a precise monitoring method using in vivo confocal microscopy in a rat double lacrimal gland removal model. Methods: Five Sprague-Dawley rats (age 8-9 weeks, male) underwent double lacrimal gland removal. Modified Schirmer's tear test, blink tests, and in vivo confocal microscopy images were acquired pre-surgery and at 1, 2, and 4 weeks post-surgery. Three individual stromal nerves were selected per eye as guide images, and images of the corresponding sub-basal nerve plexus area were acquired via volume acquisition. The same area was re-imaged in subsequent weeks. Results: After double lacrimal gland removal, tear production was reduced by 60%, and the blink rate increased 10 times compared to pre-surgery. Starting from 1 week after surgery, in vivo confocal microscopy showed increased sub-basal nerve plexus nerve fiber density with inflammatory cell infiltration at the sub-basal nerve plexus layer and remained at an elevated level at 2 and 4 weeks post-surgery. Conclusions: We demonstrated that our precise monitoring method revealed detailed changes in the corneal nerves, the epithelium, and the stroma.

Circadian disruption reduces MUC4 expression via the clock molecule BMAL1 during dry eye development.

Circadian disruption, as a result of shiftwork, jet lag, and other lifestyle factors, is a common public health problem associated with a wide range of diseases, such as metabolic disorders, neurodegenerative diseases, and cancer. In the present study, we established a chronic jet lag model using a time shift method every 3 days and assessed the effects of circadian disruption on ocular surface homeostasis. Our results indicated that jet lag increased corneal epithelial defects, cell apoptosis, and proinflammatory cytokine expression. However, the volume of tear secretion and the number of conjunctival goblet cells did not significantly change after 30 days of jet lag. Moreover, further analysis of the pathogenic mechanism using RNA sequencing revealed that jet lag caused corneal transmembrane mucin deficiency, specifically MUC4 deficiency. The crucial role of MUC4 in pathogenic progression was demonstrated by the protection of corneal epithelial cells and the inhibition of inflammatory activation following MUC4 replenishment. Unexpectedly, genetic ablation of BMAL1 in mice caused MUC4 deficiency and dry eye disease. The underlying mechanism was revealed in cultured human corneal epithelial cells in vitro, where BMAL1 silencing reduced MUC4 expression, and BMAL1 overexpression increased MUC4 expression. Furthermore, melatonin, a circadian rhythm restorer, had a therapeutic effect on jet lag-induced dry eye by restoring the expression of BMAL1, which upregulated MUC4. Thus, we generated a novel dry eye mouse model induced by circadian disruption, elucidated the underlying mechanism, and identified a potential clinical treatment.

Reticulated Retinoic Acid Synthesis is Implicated in the Pathogenesis of Dry Eye in Aqp5 Deficiency Mice.

Purpose: Abnormalities in aquaporins are implicated in the pathological progression of dry eye syndrome. Retinoic acid (RA) regulates cellular proliferation, differentiation, and apoptosis in the cornea, thereby being associated with dry eye disease (DED). The objective of this study is to explore the underlying mechanisms responsible for RA metabolic abnormalities in corneas lacking aquaporin 5 (AQP5). Methods: Dry eye (DE) models were induced via subcutaneous scopolamine hydrobromide. Aqp5 knockout (Aqp5-/-) mice and DE mice were utilized to assess corneal epithelial alterations. Tear secretion, goblet cell counts, and corneal punctate defects were evaluated. The impact of Aqp5 on RA-related enzymes and receptors was investigated using pharmacological RA or SR (A JunB inhibitor), a transcription factor JunB inhibitor, treatment in mouse corneal epithelial cells (CECs), or human corneal epithelial cells (HCECs). The HCECs and NaCl-treated HCECs underwent quantitative real-time PCR (qRT-PCR), immunofluorescent, Western blot, and TUNEL assays. The regulation of transcription factor JunB on Aldh1a1 was explored via ChIP-PCR. Results: Aqp5 and Aldh1a1 were reduced in both CECs of DE mice and NaCl-induced HCECs. Aqp5-/- mice exhibited DE phenotype and reduced Aldh1a1. RA treatment reduced apoptosis, promoted proliferation, and improved the DE phenotype in Aqp5-/- mice. JunB enrichment in the Aldh1a1 promoter was identified by ChIP-PCR. SR significantly increased Aldh1a1 expression, Ki67, and ΔNp63-positive cells, and decreased TUNEL-positive cells in CECs and HCECs. Conclusions: Our findings demonstrated the downregulation of Aqp5 expression and aberrant RA metabolism in DE conditions. Knockout of Aqp5 resulted in reduced production of RA through activation of JunB, subsequently leading to the manifestation of DE symptoms.

Multifunctional cerium oxide nanozymes with high ocular surface retention for dry eye disease treatment achieved by restoring redox balance.

Dry eye disease (DED) is a kind of multifactorial ocular surface disease that displays ocular discomfort, visual disturbance, and tear film instability. Oxidative stress is a fundamental pathogenesis in DED. An imbalance between the reactive oxygen species (ROS) level and protective enzyme action will lead to oxidative stress, cell dysfunction, tear hyperosmolarity, and inflammation. Herein, a multifunctional cerium oxide nanozyme with high ocular surface retention property was designed to neutralize over-accumulated ROS and restore redox balance. Cerium oxide nanozymes were fabricated via branched polyethylenimine-graft-poly (ethylene glycol) nucleation and dispersion, followed by phenylboronic acid (PBA) functionalization (defined as Ce@PB). Due to the dynamic chemical bonding formation between the PBA segment and the cis-diol groups in the mucin layer of the tear film, Ce@PB nanozymes possess good adhesive capability to the ocular surface, thus extending the drug's retention time. On the other hand, Ce@PB nanozymes could mimic the cascade processes of superoxide dismutase and catalase to maintain intracellular redox balance. In vitro and in vivo studies suggest that such multifunctional nanozymes possess good biocompatibility and hemocompatibility. More importantly, Ce@PB nanozymes treatment in the animal model could repair corneal epithelial defect, increase the number of goblet cells and promote tear secretion, thus achieving an effective treatment for DED. STATEMENT OF SIGNIFICANCE.

Multifunctional Cerium Oxide Nanozyme for Synergistic Dry Eye Disease Therapy.

Dry eye disease (DED) is a chronic multifactorial ocular surface disease mainly caused by the instability of tear film, characterized by a series of ocular discomforts and even visual disorders. Oxidative stress has been recognized as an upstream factor in DED development. Diquafosol sodium (DQS) is an agonist of the P2Y2 receptor to restore the integrity/stability of the tear film. With the ability to alternate between Ce3+ and Ce4+, cerium oxide nanozymes could scavenge overexpressed reactive oxygen species (ROS). Hence, a DQS-loaded cerium oxide nanozyme was designed to boost the synergistic treatment of DED. Cerium oxide with branched polyethylenimine-graft-poly(ethylene glycol) as nucleating agent and dispersant was fabricated followed with DQS immobilization via a dynamic phenylborate ester bond, obtaining the DQS-loaded cerium oxide nanozyme (defined as Ce@PBD). Because of the ability to mimic the cascade processes of superoxide dismutase and catalase, Ce@PBD could scavenge excessive accumulated ROS, showing strong antioxidant and anti-inflammatory properties. Meanwhile, the P2Y2 receptors in the conjunctival cells could be stimulated by DQS in Ce@PBD, which can relieve the incompleteness and instability of the tear film. The animal experiments demonstrated that Ce@PBD significantly restored the defect of the corneal epithelium and increased the number of goblet cells, with the promotion of tear secretion, which was the best among commercial DQS ophthalmic solutions.

The Severity of Diabetic Retinopathy Corresponds with Corneal Nerve Alterations and Ocular Discomfort of the Patient.

Diabetic retinopathy (DR) remains the leading cause of blindness in the working-age population. Its progression causes gradual damage to corneal nerves, resulting in decreased corneal sensitivity (CS) and disruption of anterior-eye-surface homeostasis, which is clinically manifested by increased ocular discomfort and dry eye disease (DED). This study included 52 DR patients and 52 sex- and age-matched controls. Ocular Surface Disease Index (OSDI) survey, tear film-related parameters, CS, and in vivo corneal confocal microscopy (IVCM) of the subbasal plexus were performed. Furthermore, all patients underwent tear sampling for neurotrophin and cytokine analysis. OSDI scores were greater in DR patients than in controls (p = 0.00020). No differences in the Schirmer test score, noninvasive tear film-break-up time (NIBUT), tear meniscus or interferometry values, bulbar redness, severity of blepharitis or meibomian gland loss were found. In the DR group, both the CS (p < 0.001), and the scotopic pupil diameter (p = 0.00008) decreased. IVCM revealed reduced corneal nerve parameters in DR patients. The stage of DR was positively correlated with the OSDI (Rs = +0.51, 95% CI: + 0.35-+0.64, p < 0.001) and negatively correlated with IVCM corneal nerve parameters and scotopic pupillometry (Rs = -0.26, 95% CI: -0.44--0.06, p = 0.0097). We found negative correlations between the OSDI and IVCM corneal innervation parameters. The DR group showed lower tear film-brain-derived neurotrophic factor (BDNF) levels (p = 0.0001) and no differences in nerve growth factor (NGF)-ß, neurotrophin (NT)-4, vascular endothelial growth factor (VEGF), interleukin (IL)-1ß, IL-4, IL-5, IL-6, or IL-12 concentrations. Tumor necrosis factor (TNF)-α, IL-2, IL-8, IL-10, granulocyte macrophage colony-stimulating factor (GM-CSF), and interferon (IFN)-γ levels were decreased among patients with DR. Corneal innervation defects have a direct impact on patients' subjective feelings. The evolution of DR appears to be associated with corneal nerve alterations, emphasizing the importance of IVCM.

Polarity-Driven Fluorescence Monitoring of Lipid Droplet Dynamics in Dry Eye Disease.

The emergence of lipid droplets (LDs) has been recognized as cellular markers of ocular surface hyperosmosis, which is recognized as a fundamental mechanism driving dry eye disease (DED), while their dynamics during DED progression and therapy remains unlocked. For this purpose, an LD-specific fluorescent probe P1 is presented in this work that exhibits highly selective and sensitive emission enhancement in response to a decreased ambient polarity (Δf) from 0.209 to 0.021. The hydrophobic nature of P1 enables specific staining of LDs, facilitating visualization of changes in polarity within these cellular structures. Utilizing P1, we observe a decrease in polarity accompanied by an increase in the size and number of LDs in hyperosmotic human corneal epithelial cells (HCECs). Furthermore, interplays between LDs and cellular organelles such as mitochondria and the Golgi apparatus are visualized, suggesting the underlying pathogenesis in DED. Notably, the variations of LDs are observed after the inhibition of ferroptosis or activation of autophagy in hyperosmotic HCECs, implying the great potential of LDs as indicators for the design and efficacy evaluation of DED drugs regarding ferroptosis or autophagy as targets. Finally, LDs are confirmed to be overproduced in corneal tissues from DED mice, and the application of clinical eye drops effectively impedes these changes. This detailed exploration underscores the significant roles of LDs as an indicator for the deep insight into DED advancement and therapy.

The Aging Lacrimal Gland of Female C57BL/6J Mice Exhibits Multinucleate Macrophage Infiltration Associated With Lipid Dysregulation.

Purpose: Loss of function of the lacrimal gland (LG), which produces the aqueous tear film, is implicated in age-related dry eye. To better understand this deterioration, we evaluated changes in lipid metabolism and inflammation in LGs from an aging model. Methods: LG sections from female C57BL/6J mice of different ages (young, 2-3 months; intermediate, 10-14 months; old,  ≥24 months) were stained with Oil Red-O or Toluidine blue to detect lipids. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis and western blotting of LG lysates determined differences in the expression of genes and proteins related to lipid metabolism. A photobleaching protocol to quench age-related autofluorescence was used in LG sections to evaluate changes in immunofluorescence associated with NPC1, NPC2, CTSL, and macrophages (F4/80, CD11b) with age using confocal fluorescence microscopy. Results: Old LGs showed increased lipids prominent in basal aggregates in acinar cells and in extra-acinar sites. LG gene expression of Npc1, Npc2, Lipa, and Mcoln2, encoding proteins involved in lipid metabolism, was increased with age. NPC1 was also significantly increased in old LGs by western blotting. In photobleached LG sections, confocal fluorescence microscopy imaging of NPC1, NPC2, and CTSL immunofluorescence showed age-associated enrichment in macrophages labeled to detect F4/80. Although mononuclear macrophages were detectable in LG at all ages, this novel multinucleate macrophage population containing NPC1, NPC2, and CTSL and enriched in F4/80 and some CD11b was increased with age at extra-acinar sites. Conclusions: Lipid-metabolizing proteins enriched in F4/80-positive multinucleated macrophages are increased in old LGs adjacent to sites of lipid deposition in acini.

Topical naltrexone increases aquaporin 5 production in the lacrimal gland and restores tear production in diabetic rats.

Diabetes mellitus is a prevalent disease that is often accompanied by ocular surface abnormalities including delayed epithelial wound healing and decreased corneal sensitivity. The impact of diabetes on the lacrimal functional unit (LFU) and the structures responsible for maintaining tear homeostasis, is not completely known. It has been shown that the Opioid Growth Factor Receptor (OGFr), and its ligand, Opioid Growth Factor (OGF), is dysregulated in the ocular surface of diabetic rats leading to overproduction of the inhibitory growth peptide OGF. The opioid antagonist naltrexone hydrochloride (NTX) blocks the OGF-OGFr pathway, and complete blockade following systemic or topical treatment with NTX restores the rate of re-epithelialization of corneal epithelial wounds, normalizes corneal sensitivity, and reverses dry eye in diabetic animal models. These effects occur rapidly and within days of initiating treatment. The present study was designed to understand mechanisms related to the fast reversal (<5 days) of dry eye by NTX in type 1 diabetes (T1D) by investigating dysregulation of the LFU. The approach involved examination of the morphology of the LFU before and after NTX treatment. Male and female adult Sprague-Dawley rats were rendered hyperglycemic with streptozotocin, and after 6 weeks rats were considered to be a T1D model. Rats received topical NTX twice daily to one eye for 10 days. During the period of treatment, tear production and corneal sensitivity were recorded. On day 11, animals were euthanized and orbital tissues including conjunctiva, eyelids, and lacrimal glands, were removed and processed for histologic examination including immunohistochemistry. Male and female T1D rats had significantly decreased tear production and corneal insensitivity, significantly decreased number and size of lacrimal gland acini, decreased expression of aquaporin-5 (AQP5) protein and decreased goblet cell size. Thus, 10 days of NTX treatment restored tear production and corneal sensitivity to normal values, increased AQP5 expression, and restored the surface area of goblet cells to normal. NTX had no effect on the number of lacrimal gland acini or the number of conjunctival goblet cells. In summary, blockade of the OGF-OGFr pathway with NTX reversed corneal and lacrimal gland complications and restored some components of tear homeostasis confirming the efficacy of topical NTX as a treatment for ocular defects in diabetes.

Combination of PEGylation and Cationization on Phospholipid-Coated Cyclosporine Nanosuspensions for Enhanced Ocular Drug Delivery.

Strong precorneal clearance mechanisms including reflex blink, constant tear drainage, and rapid mucus turnover constitute great challenges for eye drops for effective drug delivery to the ocular epithelium. In this study, cyclosporine A (CsA) for the treatment of dry eye disease (DED) was selected as the model drug. Two strategies, PEGylation for mucus penetration and cationization for potent cellular uptake, were combined to construct a novel CsA nanosuspension (NS@lipid-PEG/CKC) by coating nanoscale drug particles with a mixture of lipids, DSPE-PEG2000, and a cationic surfactant, cetalkonium chloride (CKC). NS@lipid-PEG/CKC with the mean size ∼173 nm and positive zeta potential ∼+40 mV showed promoted mucus penetration, good cytocompatibility, more cellular uptake, and prolonged precorneal retention without obvious ocular irritation. More importantly, NS@lipid-PEG/CKC recovered tear production and goblet cell density more efficiently than the commercial cationic nanoemulsion on a dry eye disease rat model. All results indicated that a combination of PEGylation and cationization might provide a promising strategy to coordinate mucus penetration and cellular uptake for enhanced drug delivery to the ocular epithelium for nanomedicine-based eye drops.

Electroacupuncture modulates the TLR4-NF-κB inflammatory signaling pathway to attenuate ocular surface inflammation in dry eyes of type 2 diabetic rats.

Bioinformatics analysis was performed to reveal the underlying pathogenesis of type 2 diabetes (T2DM) dry eye(DE) and to predict the core targets and potential pathways for electroacupuncture (EA) treatment of T2DM DE, in which key targets such as Toll-likereceptor4 (TLR4), NF-κB and Tumor necrosis factor-α (TNF-α) may be involved. Next, streptozotocin and a high-fat diet were used to generate T2DM-DE rats. Randomly picked EA, fluorometholone, model, and sham EA groups were created from successfully modelled T2DM DE rats. Six more rats were chosen as the blank group from among the normal rats. The results of DE index showed that EA improved the ocular surface symptoms.HE staining showed that EA attenuated the pathological changes in the cornea, conjunctiva and lacrimal gland of T2DM DE rats. EA decreased the expression of TLR4, MyD88, P-NF-κB P65, and TNF-α in the cornea, conjunctiva, and lacrimal gland, in accordance with immunofluorescence and Western blot data. Thus, EA reduced ocular surface symptoms and improved pathological changes of cornea, conjunctiva, and lacrimal gland induced by T2DM DE inT2DM DE rats, and the mechanism may be related to the inhibition of overactivation of the TLR4/NF-κB signaling pathway by EA and thus attenuating ocular surface inflammation.

Biochanin A: Disrupting the inflammatory vicious cycle for dry eye disease.

Dry eye disease (DED) is a complex disorder driven by several factors like reduced tear production, increased evaporation, or poor tear quality. Oxidative stress plays a key role by exacerbating the inflammatory cycle. Previous studies explored antioxidants for DED treatment due to the link between oxidative damage and inflammation. Biochanin A (BCA) is a bioisoflavone from red clover with potent anti-inflammatory effects. This study investigated BCA's therapeutic potential for DED. Human corneal epithelial cells were cultured under hyperosmotic conditions to mimic DED. BCA treatment increased cell viability and decreased apoptosis and inflammatory cytokine expression. A DED mouse model was developed using female C57BL/6 mice in a controlled low-humidity environment combined with scopolamine injections. Mice received eye drops containing phosphate-buffered saline, low-dose BCA, or high-dose BCA. The effectiveness was evaluated by measuring tear volume, fluorescein staining, eye-closing ratio, corneal sensitivity and PAS staining. The levels of inflammatory components in corneas and conjunctiva were measured to assess DED severity. Maturation of antigen-presenting cells in cervical lymph nodes was analyzed by flow cytometry. BCA eye drops effectively reduced inflammation associated with DED in mice. BCA also decreased oxidative stress levels by reducing reactive oxygen species and enhancing the nuclear translocation of nuclear factor erythroid-2-related factor 2 (Nrf2). These findings demonstrate that BCA ameliorates oxidative stress and ocular surface inflammation, indicating potential as a DED treatment by relieving oxidative damage and mitigating inflammation.

BMSC-derived exosomes regulate the Treg/Th17 balance through the miR-21-5p/TLR4/MyD88/NF-κB pathway to alleviate dry eye symptoms in mice.

Bone marrow mesenchymal stem cell (BMSC)-derived exosomes (BMSC-Exos) have a variety of biological functions and are extensively involved in the regulation of inflammatory diseases, as well as tissue repair and regeneration. However, the mechanism of action of these compounds in dry eye disease (DED) in mice is still unclear. This study demonstrated that the Treg/Th17 ratio was strongly imbalanced in DED clinical samples. BMSC-Exos can modulate the Treg/Th17 balance, improve the integrity of the corneal epithelial layer, and ameliorate DED progression in mice. Mechanistically, BMSC-Exos dramatically decreased the levels of IL-17 and IL-22; increased the levels of IL-4, IL-10, and TGF-ß1; and increased tear secretion and the number of goblet cells in the conjunctiva in mice, thus alleviating the progression of DED. This effect is achieved by BMSC-Exos through the delivery of miR-21-5p to target and restrain TLR4, thereby restraining the MyD88/NF-κB pathway. Our study showed that the upregulation of miR-21-5p in BMSC-Exos may be a therapeutic target for DED. These findings support new ideas and a basis for treating DED, as well as for further study of the application value of exosomes in alleviating DED.

Nanoceria-Mediated Cyclosporin A Delivery for Dry Eye Disease Management through Modulating Immune-Epithelial Crosstalk.

Dry eye disease (DED) affects a substantial worldwide population with increasing frequency. Current single-targeting DED management is severely hindered by the existence of an oxidative stress-inflammation vicious cycle and complicated intercellular crosstalk within the ocular microenvironment. Here, a nanozyme-based eye drop, namely nanoceria loading cyclosporin A (Cs@P/CeO2), is developed, which possesses long-term antioxidative and anti-inflammatory capacities due to its regenerative antioxidative activity and sustained release of cyclosporin A (CsA). In vitro studies showed that the dual-functional Cs@P/CeO2 not only inhibits cellular reactive oxygen species production, sequentially maintaining mitochondrial integrity, but also downregulates inflammatory processes and repolarizes macrophages. Moreover, using flow cytometric and single-cell sequencing data, the in vivo therapeutic effect of Cs@P/CeO2 was systemically demonstrated, which rebalances the immune-epithelial communication in the corneal microenvironment with less inflammatory macrophage polarization, restrained oxidative stress, and enhanced epithelium regeneration. Collectively, our data proved that the antioxidative and anti-inflammatory Cs@P/CeO2 may provide therapeutic insights into DED management.

Analysis of the mucosal chemokines CCL28, CXCL14, and CXCL17 in dry eye disease: An in vitro and clinical investigation.

Mucosal chemokines have antimicrobial properties and play an important role in mucosal immunity. However, little is known about their expression on the ocular surface. This study aimed to analyze the expression of the mucosal chemokines CCL28, CXCL14 and CXCL17 in corneal and conjunctival epithelial cells under in vitro dry eye (DE) conditions, and in conjunctival samples from healthy subjects and DE patients. Human corneal epithelial cells (HCE) and immortalized human conjunctival epithelial cells (IM-HConEpiC) were incubated under hyperosmolar (400-500 mOsM) or inflammatory (TNF-α 25 ng/mL) conditions for 6 h and 24 h to measure CCL28, CXCL14, and CXCL17 gene expression by RT-PCR and their secretion by immunobead-based analysis (CCL28, CXCL14) and ELISA (CXCL17). Additionally, twenty-seven DE patients and 13 healthy subjects were included in this study. DE-related questionnaires (OSDI, mSIDEQ and NRS) evaluated symptomatology. Ocular surface integrity was assessed using vital staining. Tactile sensitivity was measured with Cochet-Bonnet esthesiometer, and mechanic and thermal (heat and cold) sensitivity using Belmonte's non-contact esthesiometer. Subbasal nerve plexus and dendritic cell density were analyzed by in vivo confocal microscopy. Conjunctival cells from participants were collected by impression cytology to measure mucosal chemokines gene expression by RT-PCR. Our results showed that HCE and IM-HConEpiC cells increased CCL28, CXCL14, and CXCL17 secretion under hyperosmolar conditions. The gene expression of CCL28 was significantly upregulated in conjunctival samples from DE patients. CCL28 expression correlated positively with symptomatology, corneal staining, heat sensitivity threshold, and dendritic cell density. CXCL14 expression correlated positively with age, ocular pain, conjunctival staining, tactile sensitivity, and image reflectivity. CXCL17 expression correlated positively with corneal staining. These results suggest that corneal and conjunctival epithelial cells could be a source of CCL28, CXCL14, and CXCL17 on the ocular surface and that CCL28 might be involved in DE pathogenesis.