Zidovudine protects hyperosmolarity-stressed human corneal epithelial cells via antioxidant pathway

BMSC Alleviates Dry Eye by Inhibiting the ROS-NLRP3-IL-1β Signaling Axis by Reducing Inflammation Levels

PURPOSE

Bone marrow mesenchymal stem cells (BMSC) have multiple biological functions and are widely involved in regulating inflammatory diseases, tissue repair and regeneration. However, the mechanism of their action in dry eye disease (DED) is currently unclear. The purpose of this study was to investigate the effect of BMSCs in the treatment of dry eye mice and to explore its specific therapeutic mechanism.

METHODS

Mouse corneal epithelial cells (MCECs) were treated with 500 mOsM sodium chloride hypertonic solution to induce a DED cell model. The dry eye animal model was constructed by adding 5 μL 0.2% benzalkonium chloride solution to mouse eyes. Western blotting was used to detect the expression of related proteins, and flow cytometry, enzyme-linked immunosorbent assay (ELISA), terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining, hematoxylin-eosin (HE) staining, and periodic acid schiff (PAS) staining were used to detect cell and eye tissue damage.

RESULTS

The experimental results showed that BMSCs can reduce the levels of reactive oxygen species (ROS) and inflammatory factors in MCECs, promote cell proliferation, inhibit cell apoptosis, improve the integrity of the corneal epithelial layer in vivo, promote an increase in the number of goblet cells, and alleviate DED. Further exploration of the molecular mechanism of BMSCs treatment revealed that BMSCs alleviate the progression of DED by inhibiting the ROS-NLRP3-IL-1β signaling pathway.

CONCLUSION

BMSCs inhibit ROS-NLRP3-IL-1β signaling axis, reducing inflammation levels and alleviating dry eye symptoms. These findings provide new ideas and a basis for the treatment of DED and provide an experimental basis for further research on the application value of BMSCs in alleviating DED.

Potential New Target for Dry Eye Disease-Oxidative Stress

Dry eye disease (DED) is a multifactorial condition affecting the ocular surface. It is characterized by loss of tear film homeostasis and accompanied by ocular symptoms that may potentially result in damage to the ocular surface and even vision loss. Unmodifiable risk factors for DED mainly include aging, hormonal changes, and lifestyle issues such as reduced sleep duration, increased screen exposure, smoking, and ethanol consumption. As its prevalence continues to rise, DED has garnered considerable attention, prompting the exploration of potential new therapeutic targets. Recent studies have found that when the production of ROS exceeds the capacity of the antioxidant defense system on the ocular surface, oxidative stress ensues, leading to cellular apoptosis and further oxidative damage. These events can exacerbate inflammation and cellular stress responses, further increasing ROS levels and promoting a vicious cycle of oxidative stress in DED. Therefore, given the central role of reactive oxygen species in the vicious cycle of inflammation in DED, strategies involving antioxidants have emerged as a novel approach for its treatment. This review aims to enhance our understanding of the intricate relationship between oxidative stress and DED, thereby providing directions to explore innovative therapeutic approaches for this complex ocular disorder.

Puerarin alleviates hyperosmotic stress-induced oxidative stress, inflammation, apoptosis and barrier damage of human corneal epithelial cells by targeting SIRT1/NLRP3 signaling

The increase of tear osmolarity caused by excessive evaporation of tear phase is the main pathological mechanism of dry eye disease (DED). Puerarin, the major bioactive ingredient isolated from the root of the Pueraria lobata (Willd.) Ohwi, has been reported to improve ophthalmic diseases in clinic. However, the effect and the potential regulatory mechanism related to silent information regulator sirtuin 1 (SIRT1)/NOD-like receptor family pyrin domain containing 3 (NLRP3) signaling of puerarin in DED has not been evaluated. In this study, we aimed to explore the effect and mechanism of hyperosmotic stress (Hyp)-induced human corneal epithelial cell line (HCE-2). The viability of HCE-2 cells induced by Hyp with or without puerarin treatment was assessed by a CCK-8 assay. Results indicated that puerarin treatment enhanced cell viability, reduced reactive oxygen species (ROS) content, increased CAT and SOD activities, and elevated the ratio of GSH/GSSG in HCE-2 cells exposed to Hyp. Besides, TNF-α, IL-1β and IL-6 contents were decreased by puerarin. Additionally, puerarin inhibited Hyp-induced apoptosis and barrier disruption of HCE-2 cells. Moreover, molecular docking method suggested that puerarin bound to SIRT1, and upregulated SIRT1 and downregulated NLRP3 inflammasome proteins after puerarin treatment was observed. Furthermore, SIRT1 silencing alleviated the protective effects of puerarin on Hyp-induced HCE-2 cell damage. Collectively, puerarin attenuates Hyp-induced injury of HCE-2 cells by targeting regulating SIRT1/NLRP3 signaling.

BMSC reduces ROS and inflammation levels by inhibiting TLR4/MYD88/NF-κB signaling axis to alleviate dry eye

Objective To investigate the therapeutic effect of Bone marrow mesenchymal stem cells (BMSCs) on dry eye mice, and to investigate the mechanism of TLR4/MYD88/NF-κB signaling pathway on corneal injury repair in dry eye mice. Methods To establish a hypertonic dry eye cell model. Western blot for measureing the protein expressions of caspase-1, IL-1β，NLRP3 and ASC，and Rt-qpcr for mRNA expression. Flow cytometry for detecting the ROS content and apoptosis rate. CCK-8 for detecting the proliferation activity of cells, and ELISA for the levels of inflammation-related factors.The levels of inflammation-related factors were detected by ELISA. The dry eye mouse model of benzalkonium chloride was established. Three clinical parameters used to evaluate ocular surface damage, namely tear secretion, tear film rupture time and corneal sodium fluorescein staining, were measured with phenol cotton thread. Flow cytometry and TUNEL staining are both for he apoptosis rate. Western blot also for detecting the protein expressions of TLR4, MYD88, NF-κB, inflammation-related factors and apoptosis-related factors . The pathological changes were evaluated by HE and PAS staining. Results In vitro, BMSCs and inhibitors of TLR4, MYD88 and NF-κB showed decreased ROS content, decreased inflammatory factor protein level, decreased apoptotic protein level and increased mRNA expression compared with NaCl group. BMSCS partially reversed cell apoptosis induced by NaCl and improved cell proliferation. In vivo, it reduces corneal epithelial defects, goblet cell loss and inflammatory cytokine production, and increases tear production. In vitro, BMSC and inhibitors of TLR4, MYD88 and NF-κB could protect mice from apoptosis induced by hypertonic stress. In terms of mechanism, NACL-induced NLRP3 inflammasome formation, caspase-1 activation and IL-1β maturation can be inhibited. Conclusion BMSCs treatment can reduce ROS and inflammation levels and alleviate dry eye by inhibiting TLR4/MYD88/NF-κBsignaling pathway.

Cyclosporin A improves the hyperosmotic response in an experimental dry eye model by inhibiting the HMGB1/TLR4/NF-κB signaling pathway

Hyperosmolarity is closely related to dry eye disease (DED), which induces corneal epithelial cell structure and dysfunction leading to ocular surface inflammation. Cyclosporine A (CSA) is a cyclopeptide consisting of 11 deduced amino acids. It has an immunosuppressive effect and shows a vital function in inhibiting the inflammatory response. The mechanism of CSA in DED is still not entirely clear. This experiment aimed to investigate the possible mechanism of CSA in the hyperosmotic DED model. This study found that CSA can inhibit the transcript levels of DED high mobility group protein 1 (HMGB1), Toll-like receptor 4 (TLR4) and nuclear transcription factor κB (NF-κB) in signaling pathways. In addition, the study also found that 550 mOsm/L can induce the formation of DED models in vivo or in vitro. Furthermore, different concentrations of CSA have different effects on the expression of HMGB1 in human corneal epithelial cells under hyperosmotic stimulation, and high concentrations of CSA may increase the expression of HMGB1. In addition, CSA effectively reduced the corneal fluorescence staining score of the DE group and increased the tear volume of mice. Therefore, this experimental investigation might supply new evidence for the mechanism of CSA in DED, provide a potential new therapy for treating DED, and provide a theoretical basis for CSA treatment of DED.

Protection of Retinal Function by Nucleoside Reverse Transcriptase Inhibitors Following Retinal Ischemia/Reperfusion Injury

Purpose: Retinal ischemia/reperfusion (I/R) injury is a common cause of visual impairment and blindness for which there remain limited treatment options. Nucleoside reverse transcriptase inhibitors (NRTIs), such as zidovudine (AZT), have been shown to block the NLRP3 inflammasome and prevent retinal degeneration in a mouse model of age-related macular degeneration. The NLRP3 inflammasome has also been shown to be triggered in I/R injury. Therefore, we studied the neuroprotective effects of AZT using a pressure-induced retinal ischemia mouse model. Methods: C57BL/6J mice were randomly assigned to 1 of 2 treatment groups: vehicle-treated retinal I/R injury (n = 6) or AZT-treated retinal I/R injury (n = 6). Vehicle (1% dimethyl sulfoxide [DMSO] in phosphate-buffered saline [PBS]) or AZT 50 mg/kg in 1% DMSO in PBS were injected intraperitoneally twice daily for 5 days. On day 2 of treatment, retinal ischemia was induced by transient elevation of intraocular pressure for 45 min. Scotopic electroretinography (ERG) was used to quantify retinal function before and 1 week after retinal ischemic insult. Retinal morphology was examined 1 week after ischemic insult. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays and caspase 1 immunostaining was performed 24 h after retinal I/R injury. Results: Following I/R injury, ERG a- and b-wave amplitudes were significantly reduced in the vehicle-treated mice. AZT treatment significantly attenuated I/R-induced loss of retinal function as compared with vehicle-treated mice. Additionally, AZT-treated mice experienced significantly less inner retinal thinning as compared with vehicle-treated mice. TUNEL-positive cells were prevalent in the vehicle-treated I/R injury mouse retinas compared with the AZT-treated I/R injury mouse retinas. More caspase-1 immunoreactivity was detected in ganglion cell layer and inner nuclear layer (INL) in vehicle-treated I/R injury group than in AZT-treated I/R injury group. Conclusion: AZT treatment resulted in relative preservation of retinal structure and function following ischemic insult as compared with controls. This suggests AZT may have therapeutic value in the management of retinal ischemic diseases.

Synthesis of fluorescent drug molecules for competitive binding assay based on molecularly imprinted polymers

Fluorescent immunosorbent assay (FIA) is very promising for sensitive and selective analysis in bio-medical applications. Here, we proposed an assay, using fluorescent engineering of analytes and the corresponding molecularly imprinted polymers (MIPs) as a plastic antibody. Three drug molecules (metronidazole, zidovudine and lamivudine) were condensed with 9-aminoacridine, using succinic anhydride as a spacer. The target products were characterized with ¹H-NMR, IR and mass spectrometry. UV-vis absorption and fluorescent properties of the fluorophore-labeled drug molecules were investigated. Feasibility of the fluorescent biomimetic immunosorbent assay based on MIPs was demonstrated in the solution. This work will provide sound foundation for the future application in real sample.

Drug molecules (metronidazole, zidovudine and lamivudine) were successfully labelled with a fluorescent reagent and used to develop fluorescent biomimetic immunosorbent assays using molecularly imprinted polymers in the place of natural antibody.