Achyranthis radix Extract Improves Urban Particulate Matter-Induced Dry Eye Disease

Particulate matter 2.5 stimulates pyroptosis and necroptosis via the p38 MAPK/Akt/NF-κB signaling pathway in human corneal epithelial cells

Particulate matter 2.5 (PM2.5) exposure poses significant health risks, particularly to the eyes. This study aimed to investigate the cytotoxic effects of PM2.5 on human corneal epithelial cells (HCECs) and to elucidate the mechanisms involved in pyroptosis and necroptosis. HCECs were exposed to PM2.5, and cytotoxicity, reactive oxygen species (ROS) levels, and the expression of pyroptosis- and necroptosis-related proteins were assessed. The roles of nuclear factor-kappa B (NF-κB) and nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome signaling pathways were also investigated. Exposure to PM2.5 caused a dose-dependent decrease in cell viability, accompanied by significant NLRP3 inflammasome activation, leading to pyroptosis and the release of pro-inflammatory cytokines. Enhanced ROS generation and mitochondrial dysfunction have also been observed, along with indicators of necroptosis, such as increased levels of mixed-lineage kinase domain-like proteins. Importantly, activation of the NF-κB signaling pathway was crucial for these responses. The suppression of p38 mitogen-activated protein kinase (MAPK) and activation of protein kinase B (Akt) using pharmacological modulators SB203580 and SC79, respectively, significantly reduced PM2.5-mediated cellular damage. These findings indicate that p38 MAPK inhibition and Akt activation are key regulatory mechanisms that help attenuate the deleterious effects of PM2.5 on HCECs. In conclusion, our findings offer new insights into the mechanisms by which PM2.5 induces pyroptosis and necroptosis in HCECs, especially by activating the NLRP3 inflammasome and NF-κB signaling pathways. The critical regulatory roles of p38 MAPK and Akt underscore their potential as therapeutic targets to alleviate PM-induced ocular damage.

Therapeutic Potential of Herbal Medicines in Combating Particulate Matter (PM)-Induced Health Effects: Insights from Recent Studies

Particulate matter (PM), particularly fine (PM2.5) and ultrafine (PM0.1) particles, originates from both natural and anthropogenic sources, such as biomass burning and vehicle emissions. These particles contain harmful compounds that pose significant health risks. Upon inhalation, ingestion, or dermal contact, PM can penetrate biological systems, inducing oxidative stress, inflammation, and DNA damage, which contribute to a range of health complications. This review comprehensively examines the protective potential of natural products against PM-induced health issues across various physiological systems, including the respiratory, cardiovascular, skin, neurological, gastrointestinal, and ocular systems. It provides valuable insights into the health risks associated with PM exposure and highlights the therapeutic promise of herbal medicines by focusing on the natural products that have demonstrated protective properties in both in vitro and in vivo PM2.5-induced models. Numerous herbal medicines and phytochemicals have shown efficacy in mitigating PM-induced cellular damage through their ability to counteract oxidative stress, suppress pro-inflammatory responses, and enhance cellular defense mechanisms. These combined actions collectively protect tissues from PM-related damage and dysfunction. This review establishes a foundation for future research and the development of effective interventions to combat PM-related health issues. However, further studies, including in vivo and clinical trials, are essential to evaluate the safety, optimal dosages, and long-term effectiveness of herbal treatments for patients under chronic PM exposure.

Efficacy and Safety of Useul for Dry Eye Disease: Protocol for a Randomized, Double-Blind, Placebo-Controlled, Parallel, Phase 2 Clinical Trial

Introduction: Dry eye disease (DED) is a very frequently encountered ocular disease, making it a growing public health burden. However, current treatments for DED present unmet medical needs owing to their side effects or ineffectiveness. Therefore, an effective and safe therapeutic agent to manage DED is needed. Method and Analysis: We planned a phase 2, dose-finding, double-blind, randomized placebo-controlled trial to evaluate the efficacy and safety of two different doses of USL (Useul), the extract of Achyranthis Radix, compared with placebo, for DED. USL has been found to protect against DED by inducing tear secretion and improving corneal irregularity via anti-inflammatory effects, which will provide new therapeutic options. One hundred and twenty participants will be enrolled, after assessing the inclusion/exclusion criteria, at Daejeon University Daejeon Korean Medicine Hospital. Enrolled participants will be allocated to standard-dose USL, high-dose USL, or placebo groups in a 1:1:1 ratio and will be required to administer the trial medication twice a day for 12 weeks and visit the clinic five times. For efficacy outcomes, objective endpoints of fluorescein corneal staining score, tear break-up time, Schirmer's test, and meibomian test and subjective endpoints of Ocular Surface Disease Index, visual analog scale, Standard Patient Evaluation for Eye Dryness-II, and biomarkers will be assessed throughout the trial. Safety will be assessed based on adverse events, vital signs, laboratory tests, visual acuity, and intraocular pressure. Discussion: Our study results are expected to provide clinical evidence for the use of DED as an effective and safe agent for DED.

Achyranthis radix Extract Enhances Antioxidant Effect of Placenta-Derived Mesenchymal Stem Cell on Injured Human Ocular Cells

Age-related ocular diseases such as age-related macular degeneration, glaucoma, and diabetic retinopathy are major causes of irreversible vision impairment in the elderly. Conventional treatments focus on symptom relief and disease slowdown, often involving surgery, but fall short of providing a cure, leading to substantial vision loss. Regenerative medicine, particularly mesenchymal stem cells (MSCs), holds promise for ocular disease treatment. This study investigates the synergistic potential of combining placenta-derived MSCs (PD-MSCs) with Achyranthis radix extract (ARE) from Achyranthes japonica to enhance therapeutic outcomes. In a 24-h treatment, ARE significantly increased the proliferative capacity of PD-MSCs and delayed their senescence (* p < 0.05). ARE also enhanced antioxidant capabilities and increased the expression of regeneration-associated genes in an in vitro injured model using chemical damages on human retinal pigment epithelial cell line (ARPE-19) (* p < 0.05). These results suggest that ARE-primed PD-MSC have the capability to enhance the activation of genes associated with regeneration in the injured eye via increasing antioxidant properties. Taken together, these findings support the conclusion that ARE-primed PD-MSC may serve as an enhanced source for stem cell-based therapy in ocular diseases.

Mechanisms of PM10 Disruption of the Nrf2 Pathway in Cornea

We have previously shown that PM10 exposure causes oxidative stress and reduces Nrf2 protein levels, and SKQ1 pre-treatment protects against this damage in human corneal epithelial cells (HCE-2). The current study focuses on uncovering the mechanisms underlying acute PM10 toxicity and SKQ1-mediated protection. HCE-2 were pre-treated with SKQ1 and then exposed to 100 μg/mL PM10. Cell viability, oxidative stress markers, programmed cell death, DNA damage, senescence markers, and pro-inflammatory cytokines were analyzed. Nrf2 cellular location and its transcriptional activity were determined. Effects of the Nrf2 inhibitor ML385 were similarly evaluated. Data showed that PM10 decreased cell viability, Nrf2 transcriptional activity, and mRNA levels of antioxidant enzymes, but increased p-PI3K, p-NFκB, COX-2, and iNOS proteins levels. Additionally, PM10 exposure significantly increased DNA damage, phosphor-p53, p16 and p21 protein levels, and β-galactosidase (β-gal) staining, which confirmed the senescence. SKQ1 pre-treatment reversed these effects. ML385 lowered the Nrf2 protein levels and mRNA levels of its downstream targets. ML385 also abrogated the protective effects of SKQ1 against PM10 toxicity by preventing the restoration of cell viability and reduced oxidative stress. In conclusion, PM10 induces inflammation, reduces Nrf2 transcriptional activity, and causes DNA damage, leading to a senescence-like phenotype, which is prevented by SKQ1.

Effects of particulate matter exposure on the expression of the SARS-CoV-2 ACE2 receptor in ocular surface tissues and cells

Particulate matter (PM) has been reported to be one of the risk factor for COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, although the ocular surface is deeply affected by both PM exposure and SARS-COV-2 infection, no studies have investigated the effects of PM exposure on the ocular route of SARS-COV-2 infection. To this end, we explored the effects of PM on the expression of SARS-COV-2-associated receptors and proteins in ocular surface. Herein, short- and long-term PM-exposed rat models were established by topically administering PM for 3 and 10 days, respectively. Immortalized human corneal epithelial cells (HCECs) and human conjunctival epithelial cells (HCjECs) were exposed to PM. ACE2, TMPRSS2, CD147, and ADAM17 expression levels were measured by western blot analysis. Our results show that short-term PM exposure had little effect on the expressions of ACE2, TMPRSS2, and CD147 in ocular surface tissues. However, long-term PM exposure decreased the ACE2 expression in conjunctival tissues and increased the CD147 expression in corneal or conjunctival tissues. PM exposure reduced the ACE2 expression by increasing the ADAM17 expression and ACE2 shedding level in HCECs and HCjECs. Our findings suggest that long-term PM exposure down-regulate the expression of the SARS-CoV-2 receptor ACE2 in conjunctival tissues through ADAM17-dependent ACE2 shedding. However, long-term PM exposure up-regulates the expression of another SARS-CoV-2 receptor CD147 in ocular surface tissues, accompanied by ocular surface damage and cytotoxicity. This study provides a new insight into uncovering potential risk factors for infection with SARS-CoV-2 via the ocular route.

Inhibition of Urban Particulate Matter-Induced Airway Inflammation by RIPK3 through the Regulation of Tight Junction Protein Production

Urban particulate matter (UPM) is a high-hazard cause of various diseases in humans, including in the respiratory tract, skin, heart, and even brain. Unfortunately, there is no established treatment for the damage caused by UPM in the respiratory epithelium. In addition, although RIPK3 is known to induce necroptosis, its intracellular role as a negative regulator in human lungs and bronchial epithelia remains unclear. Here, the endogenous expression of RIPK3 was significantly decreased 6 h after exposure to UPM. In RIPK3-ovexpressed cells, RIPK3 was not moved to the cytoplasm from the nucleus. Interestingly, the overexpression of RIPK3 dramatically decreased TEER and F-actin formation. Its overexpression also decreased the expression of genes for pro-inflammatory cytokines (IL-6 and IL-8) and tight junctions (ZO-1, -2, -3, E-cadherin, and claudin) during UPM-induced airway inflammation. Importantly, overexpression of RIPK3 inhibited the UPM-induced ROS production by inhibiting the activation of iNOS and eNOS and by regulating mitochondrial fission processing. In addition, UPM-induced activation of the iκB and NF-κB signaling pathways was dramatically decreased by RIPK3, and the expression of pro-inflammatory cytokines was decreased by inhibiting the iκB signaling pathway. Our data indicated that RIPK3 is essential for the UPM-induced inflammatory microenvironment to maintain homeostasis. Therefore, we suggest that RIPK3 is a potential therapeutic candidate for UPM-induced pulmonary inflammation.

Airborne Exposure of the Cornea to PM10 Induces Oxidative Stress and Disrupts Nrf2 Mediated Anti-Oxidant Defenses

The purpose of this study is to test the effects of whole-body animal exposure to airborne particulate matter (PM) with an aerodynamic diameter of <10 μm (PM10) in the mouse cornea and in vitro. C57BL/6 mice were exposed to control or 500 µg/m3 PM10 for 2 weeks. In vivo, reduced glutathione (GSH) and malondialdehyde (MDA) were analyzed. RT-PCR and ELISA evaluated levels of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling and inflammatory markers. SKQ1, a novel mitochondrial antioxidant, was applied topically and GSH, MDA and Nrf2 levels were tested. In vitro, cells were treated with PM10 ± SKQ1 and cell viability, MDA, mitochondrial ROS, ATP and Nrf2 protein were tested. In vivo, PM10 vs. control exposure significantly reduced GSH, corneal thickness and increased MDA levels. PM10-exposed corneas showed significantly higher mRNA levels for downstream targets, pro-inflammatory molecules and reduced Nrf2 protein. In PM10-exposed corneas, SKQ1 restored GSH and Nrf2 levels and lowered MDA. In vitro, PM10 reduced cell viability, Nrf2 protein, and ATP, and increased MDA, and mitochondrial ROS; while SKQ1 reversed these effects. Whole-body PM10 exposure triggers oxidative stress, disrupting the Nrf2 pathway. SKQ1 reverses these deleterious effects in vivo and in vitro, suggesting applicability to humans.

Topical Porphyrin Antioxidant Protects Against Ocular Surface Pathology in a Novel Rabbit Model for Particulate Matter-Induced Dry Eye Disease

Purpose: Particulate matter (PM) is a primary cause for the development of acute and chronic dry eye disease, especially irritant-induced conjunctivitis. The purpose of the present study was to determine the effects of fine atmospheric PM on the rabbit ocular surface, and determine the protective effects of a synthetic antioxidant, manganese(III) tetrakis(1-methyl-4-pyridyl) porphyrin (Mn-TM-2-PyP), in vitro and in vivo. Methods: Rabbit corneal epithelial cells (SIRC) were exposed to increasing concentrations of PM to determine the effects on cell motility and viability. The in vivo effects of topically instilled PM were tested in New Zealand White rabbits. Comprehensive ophthalmic exams and corneal fluorescein staining were performed. Results: Exposure to PM resulted in dose-dependent cell death and impaired cellular motility; Mn-TM-2-PyP protected against PM-induced cytotoxicity and significantly increased SIRC cell motility. In vivo, exposure to PM (5 mg/ml, topical, 3 times daily for 7 days) resulted in signs of dry eye, notably hyperemia, increased corneal fluorescein staining, and decreased tear volumes. Mn-TM-2-PyP significantly improved hyperemia and corneal fluorescein readouts but had no effect on tear production. Lifitegrast (Xiidra^®) showed similar pharmacologic efficacy to Mn-TM-2-PyP. Conclusion: Overall, these data provide evidence that PM induces phenotypes of ocular surface disease responsive to antioxidant and immunosuppressant therapy. To our knowledge this is the first report of a large animal model to study PM-induced ocular surface disease. The present work provides standardized experimental paradigms for the comprehensive in vitro and in vivo testing of novel therapeutic approaches targeting PM-induced conjunctivitis and dry-eye.

Necroptosis Contributes to Airborne Particulate Matter-Induced Ocular Surface Injury

In this study, we explored the role of necroptosis in the pathogenesis of ocular surface injury caused by airborne particulate matter (PM). Human corneal epithelial (HCE) cells and mouse ocular surface were treated with PM exposure and compared with non-exposed groups. The expression of necroptosis-related proteins was measured by immunoblotting in HCE cell groups. Cell damages were detected using CCK-8, flow cytometry, and immunofluorescence staining. In the mouse model, hematoxylin and eosin (H&E) staining and corneal fluorescein sodium staining were assessed. In addition, the expression of inflammatory cytokines and mucin were examined via Enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining and/or quantitative RT -PCR (qRT-PCR), both in vitro and in vivo. Our research showed that PM exposure may trigger HCE cell damage via necroptosis. Necrostatin-1(Nec-1), one of the specific inhibitors of necroptosis, can markedly reduce PM-induced HCE cell damage. HCE cell damage markers included decreased cell viability, increased intracellular reactive oxygen species (ROS) levels, and loss of mitochondrial membrane potential. At the same time, Nec-1 inhibited the increased inflammatory cytokines and the decreased mucin expression caused by PM exposure in HCE cells. Nec-1 also reduced corneal inflammation and mucin underproduction in mouse ocular surface after PM exposure. Our study demonstrated that necroptosis is involved in the pathogenesis of PM exposure-related ocular surface injury, including inflammation and insufficient mucin production in the cornea, which can be rescued by inhibitor Nec-1. This suggests Nec-1 could be a novel therapeutic target for ocular surface disorders, especially dry eye disease, which is caused by the exacerbation of airborne PM pollution.

Retrospective evaluation of the curative effect of traditional Chinese medicine on dry eye disease

Dry eye disease (DED) is a multifactorial illness with an increasingly high global prevalence and multiple risk factors that widely influences patients’ daily lives. It is essential to identify treatments with few or no side effects for patients with DED. We have reviewed studies published from 2001 to 2020 that investigated traditional Chinese medicine (TCM) and integrated Chinese and Western medicine for DED treatment. Current Chinese medicines used in DED therapy were categorized into four types, namely anti-oxidants, anti-inflammatory agents, hormone-like agents, and cell-repairing agents. Compound herbs, including Chi-Ju-Di-Huang-Wan and Qiming granule, can effectively alleviate dry eye symptoms. Moreover, patients with DED who were treated with Western medicine combined with TCM experienced significantly magnified therapeutic effects and reasonable costs of treatment. In conclusion, TCM can be a promising approach for treating DED, and combined treatment with TCM and Western drugs may represent a new strategy for improving the curative effect.

Animal models of dry eye disease: Useful, varied and evolving (Review)

Dry eye disease (DED), which is a prevalent disease that still lacks successful treatment options, remains a major challenge in ophthalmology. Multiple animal models of DED have been used to decipher its pathophysiology and to develop novel treatments. These models use mice, rats, rabbits, cats, dogs and non-human primates. Each model assesses aspects of DED by focusing on elements of the lacrimal functional unit, which controls the homeostasis of the tear film. The present review outlines representative DED animal models and assesses their contribution to the study of DED. Murine models are the most extensively used, followed by rabbit models; the latter offer the advantage of larger eyes, a favorable biochemical profile for drug studies, experimental ease and relatively low cost, contrasting with non-human primates, which, although closer to humans, are not as accessible and are expensive. No comprehensive ‘ideal’ animal model encompassing all aspects of human DED exists nor is it feasible. Investigators often choose an animal model based on their experimental needs and the following four features of a given model: The size of the eye, its biochemical composition, the available research reagents and cost. As research efforts in DED expand, more refined animal models are needed to supplement the enormous contribution made to date by existing models.

The Protective Effect of Topical Spermidine on Dry Eye Disease with Retinal Damage Induced by Diesel Particulate Matter2.5

Air pollutants, especially ambient fine particulate matter2.5, may contribute to various ocular surface disorders, including dry eye disease, keratitis and conjunctivitis. A natural polyamine spermidine has a protective effect on the retina and optic nerve; however, no study has been conducted on the application of spermidine in particulate matter2.5-induced dry eye disease. In the present study, we investigated the effect of spermidine eye drops in topically exposed particulate matter2.5-induced dry eye models of Sprague-Dawley rats, by hematological, biochemical and histological evaluation. Spermidine eye drops attenuated the particulate matter2.5 exposure-induced reduction of tear secretion and corneal epithelial damage. Furthermore, spermidine protected against conjunctival goblet cell loss and retinal ganglion cell loss induced by particulate matter2.5. Additionally, spermidine markedly prevented particulate matter2.5-induced infiltration of cluster of differentiation3⁺ and cluster of differentiation4⁺ T lymphocytes and F4/80⁺ macrophages on lacrimal gland. Moreover, over expression of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-6 and interleukin-17 in the lacrimal gland and cornea. Meanwhile, the levels of serum total cholesterol and low-density lipoprotein cholesterol were markedly increased by topical exposure to particulate matter2.5, but this change in the lipid profile was decreased by spermidine. Taken together, spermidine may have protective effects against particulate matter2.5-induced dry eye symptoms via stabilization of the tear film and suppression of inflammation and may in part contribute to improving retinal function and lipid metabolism disorder.

The Protective Effect of Oral Application of Corni Fructus on the Disorders of the Cornea, Conjunctiva, Lacrimal Gland and Retina by Topical Particulate Matter 2.5

Particulate matter 2.5 (PM_2.5) may aggravate dry eye disease (DED). Corni Fructus (CF), which is fruit of Cornus officinalis Sieb. et Zucc., has been reported to have various beneficial pharmacological effects, whereas the effect of CF on the eye is still unknown. Therefore, in this study, we investigated the effect of oral administration of water extract of CF (CFW) on the eye, hematology, and biochemistry in a DED model induced by topical exposure to PM_2.5. Furthermore, the efficacy of CFW compared with cyclosporine (CsA), an anti-inflammatory agent, and lutein, the posterior eye-protective agent. Sprague-Dawley rats were topically administered 5 mg/mL PM_2.5 in both eyes four times daily for 14 days. During the same period, CFW (200 mg/kg and 400 mg/kg) and lutein (4.1 mg/kg) were orally administered once a day. All eyes of rats in the 0.05% cyclosporine A (CsA)-treated group were topically exposed to 20 μL of CsA, twice daily for 14 days. Oral administration of CFW attenuated the PM_2.5-induced reduction of tear secretion and corneal epithelial damage. In addition, CFW protected against goblet cell loss in conjunctiva and overexpression of inflammatory factors in the lacrimal gland following topical exposure to PM_2.5. Furthermore, CFW markedly prevented PM_2.5-induced ganglion cell loss and recovered the thickness of inner plexiform layer. Meanwhile, CFW treatment decreased the levels of total cholesterol and low-density lipoprotein cholesterol in serum induced by PM_2.5. Importantly, the efficacy of CFW was superior or similar to that of CsA and lutein. Taken together, oral administration of CFW may have protective effects against PM_2.5-induced DED symptoms via stabilization of the tear film and suppression of inflammation. Furthermore, CFW may in part contribute to improving retinal function and lipid metabolism disorder.

Evaluation of oral toxicity and genotoxicity of Achyranthis Radix extract

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Achyranthes bidentata Blume, Achyranthis Radix (AR), is used as a traditional medicine ingredient in East Asia. It has anti-inflammatory, anti-oxidative, and anti-diabetic activities.

AIM OF THE STUDY

In the present study, we aimed to evaluate the oral toxicity and genotoxicity of single-dose and 4-week repeated-doses of AR hot water extract (ARE), under the good laboratory practice principles.

MATERIALS AND METHODS

For oral toxicity studies, SD rats (n = 5 per sex and group) were administered ARE at concentrations of 500, 1000, and 2000 mg/kg/day once (single dose) or once per day for 4 weeks (repeated dose). The non-clinical genotoxicity study consisted of bacterial reverse mutation using Escherichia coli (WP2 uvrA) and Salmonella typhimurium (TA98, TA100, TA1535, and TA1537), in vitro chromosomal aberration test with Chinese hamster lung cells (CHL/IU), and in vivo mouse bone marrow micronucleus test using bone marrow cells collected from male ICR mice (n = 5) that were orally administered ARE.

RESULTS

In the single-dose oral toxicity study, mortality and treatment-related changes in body weight were not observed throughout the study, and the lethal dose was estimated to be > 2000 mg/kg in rats. In the 4-week repeated-dose oral toxicity study, ARE did not induce significant changes in body weight, organ weight, food intake, or hematological and serum biochemical parameters in any group. In the bacterial reverse mutation test, ARE did not induce gene mutations in any tested strain. In the chromosomal aberration test, ARE did not cause chromosomal aberrations. The micronucleus test showed no significant increase in the number of micronucleated polychromatic erythrocytes or the mean ratio of polychromatic to total erythrocytes.

CONCLUSIONS

These results showed that ARE does not induce oral toxicity and genotoxicity in the in vivo and in vitro test systems.

Urban Aerosol Particulate Matter Promotes Necrosis and Autophagy via Reactive Oxygen Species-Mediated Cellular Disorders that are Accompanied by Cell Cycle Arrest in Retinal Pigment Epithelial Cells

Urban particulate matter (UPM) is recognized as a grave public health problem worldwide. Although a few studies have linked UPM to ocular surface diseases, few studies have reported on retinal dysfunction. Thus, the aim of the present study was to evaluate the influence of UPM on the retina and identify the main mechanism of UPM toxicity. In this study, we found that UPM significantly induced cytotoxicity with morphological changes in ARPE-19 human retinal pigment epithelial (RPE) cells and increased necrosis and autophagy but not apoptosis. Furthermore, UPM significantly increased G2/M arrest and simultaneously induced alterations in cell cycle regulators. In addition, DNA damage and mitochondrial dysfunction were remarkably enhanced by UPM. However, the pretreatment with the potent reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) effectively suppressed UPM-mediated cytotoxicity, necrosis, autophagy, and cell cycle arrest. Moreover, NAC markedly restored UPM-induced DNA damage and mitochondrial dysfunction. Meanwhile, UPM increased the expression of mitophagy-regulated proteins, but NAC had no effect on mitophagy. Taken together, although further studies are needed to identify the role of mitophagy in UPM-induced RPE injury, the present study provides the first evidence that ROS-mediated cellular damage through necrosis and autophagy is one of the mechanisms of UPM-induced retinal disorders.

Long-Term Exposure to Urban Particulate Matter on the Ocular Surface and the Incidence of Deleterious Changes in the Cornea, Conjunctiva and Retina in Rats

We investigated the time-dependent deleterious ocular changes induced by urban particulate matter (UPM) in vitro and in vivo. UPM treatment decreased human corneal epithelial cell migration and survival. Fluorescein scores were consistently increased by UPM application for 16 weeks. One week of rest at 2 or 4 weeks led to a recovery trend, whereas two weeks of rest at 8 weeks induced no change. UPM treatment decreased the tear film break-up time at 2 weeks, which was thereafter maintained until 16 weeks. No changes were found after periods of rest. UPM-treated eyes exhibited greater corneal epithelium thickness than normal eyes at 2 weeks, which recovered to normal at 4 and 8 weeks and was significantly decreased at 16 weeks. Apoptotic cell number in the epithelium was increased at 2 weeks, which remained constant except at 8 weeks. IL-6 expression in the cornea of the right eye continually increased for 16 weeks, and significant recovery was only observed at 8 weeks after 2 weeks of rest. Ocular pressure was significantly increased in the right eye at 12 and 16 weeks. Topical UPM application to the eye induced deleterious changes to various closely related parts of the eye.

Achyranthis radix Extract-Loaded Eye Drop Formulation Development and Novel Evaluation Method for Dry Eye Treatment

Recently, Achyranthis radix extract has been studied as a therapeutic agent for dry eye disease that occurs from fine dust. The aim of this study was the development of Achyranthis radix extract-loaded eye drop formulations using lubricants, generally used for artificial tear eye drops. Ecdysterone was used as a marker compound for Achyranthis radix extract and 1% Achyranthis radix extract solution contained 14.37 ± 0.04 μg/mL of ecdysterone. Before formulation studies, a new method was performed to evaluate pigmentation, which might be caused by eye drops of herbal extract. A comparative study of the water retention ability of each formulation and ability to prevent the death of conjunctival epithelial cells in dry conditions was conducted. Moreover, treatment of Achyranthis radix extract (USL) eye drop formulation exhibited a significant inhibitory effect on inflammation in a concentration-dependent manner. The long-term and accelerated stability tests showed that lubricants could contribute to the stability of herbal extracts in solution. In conclusion, hyaluronic acid showed a good effect on the development of eye drop formulation using Achyranthis radix extracts for treating dry eye disease.