1
|
Lucius A, Chhatwal S, Valtink M, Reinach PS, Li A, Pleyer U, Mergler S. L-Carnitine Suppresses Transient Receptor Potential Vanilloid Type 1 Activation in Human Corneal Epithelial Cells. Int J Mol Sci 2023; 24:11815. [PMID: 37511574 PMCID: PMC10380586 DOI: 10.3390/ijms241411815] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Tear film hyperosmolarity induces dry eye syndrome (DES) through transient receptor potential vanilloid type 1 (TRPV1) activation. L-carnitine is a viable therapeutic agent since it protects against this hypertonicity-induced response. Here, we investigated whether L-carnitine inhibits TRPV1 activation by blocking heat- or capsaicin-induced increases in Ca2+ influx or hyperosmotic stress-induced cell volume shrinkage in a human corneal epithelial cell line (HCE-T). Single-cell fluorescence imaging of calcein/AM-loaded cells or fura-2/AM-labeled cells was used to evaluate cell volume changes and intracellular calcium levels, respectively. Planar patch-clamp technique was used to measure whole-cell currents. TRPV1 activation via either capsaicin (20 µmol/L), hyperosmolarity (≈450 mosmol/L) or an increase in ambient bath temperature to 43 °C induced intracellular calcium transients and augmented whole-cell currents, whereas hypertonicity induced cell volume shrinkage. In contrast, either capsazepine (10 µmol/L) or L-carnitine (1-3 mmol/L) reduced all these responses. Taken together, L-carnitine and capsazepine suppress hypertonicity-induced TRPV1 activation by blocking cell volume shrinkage.
Collapse
Affiliation(s)
- Alexander Lucius
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Sirjan Chhatwal
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Monika Valtink
- Faculty of Medicine, Institute of Anatomy, TU Dresden, 01216 Dresden, Germany
- Equality and Diversity Unit, Faculty of Medicine, TU Dresden, 01307 Dresden, Germany
| | - Peter S Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325027, China
| | - Aruna Li
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Uwe Pleyer
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Stefan Mergler
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| |
Collapse
|
2
|
Lai YH, Lee PY, Lu CY, Liu YR, Wang SC, Liu CC, Chang YC, Chen YH, Su CC, Li CY, Liu PL. Thrombospondin 1-induced exosomal proteins attenuate hypoxia-induced paraptosis in corneal epithelial cells and promote wound healing. FASEB J 2021; 35:e21200. [PMID: 33341997 DOI: 10.1096/fj.202001106rrr] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/15/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022]
Abstract
Thrombospondin-1 (TSP1) is involved in corneal wound healing caused by chemical injury. Herein, we examined the effects of TSP1 on hypoxia-induced damages and wound-healing activity in human corneal epithelial (HCE) cells. Exosomal protein expression was determined using liquid chromatography-tandem mass spectrometry, and HCE cell migration and motility were examined through wound-healing assay and time-lapse microscopy. Reestablishment of cell junctions by TSP1 was assessed through confocal microscopy and 3D image reconstruction. Our results show that CoCl2 -induced hypoxia promoted HCE cell death by paraptosis. TSP1 protected these cells against paraptosis by attenuating mitochondrial membrane potential depletion, swelling and dilation of endoplasmic reticulum and mitochondria, and mitochondrial fission. Exosomes isolated from HCE cells treated with TSP1 contained wound healing-associated proteins that were taken up by HCE cells to promote tissue remodeling and repair. TSP1 protected HCE cells against hypoxia-induced damages and inhibited paraptosis progression by promoting cell migration, cell-cell adhesion, and extracellular matrix remodeling. These findings indicate that TSP1 ameliorates hypoxia-induced paraptosis in HCE cells and promotes wound healing and remodeling by regulating exosomal protein expression. TSP1 may, therefore, play important roles in the treatment of hypoxia-associated corneal diseases.
Collapse
Affiliation(s)
- Yu-Hung Lai
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Ophthalmology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Yen Lee
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chi-Yu Lu
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Ru Liu
- Department of Respiratory Therapy, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shu-Chi Wang
- Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ching-Chih Liu
- Department of Ophthalmology, Chi Mei Medical Center, Tainan, Taiwan
| | - Yo-Chen Chang
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Ophthalmology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yung-Hsiang Chen
- Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Chia-Cheng Su
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chia-Yang Li
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Len Liu
- Department of Respiratory Therapy, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| |
Collapse
|
3
|
Rajaiya J, Saha A, Ismail AM, Zhou X, Su T, Chodosh J. Adenovirus and the Cornea: More Than Meets the Eye. Viruses 2021; 13:293. [PMID: 33668417 DOI: 10.3390/v13020293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/07/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022] Open
Abstract
Human adenoviruses cause disease at multiple mucosal sites, including the respiratory, gastrointestinal, and genitourinary tracts, and are common agents of conjunctivitis. One site of infection that has received sparse attention is the cornea, a transparent tissue and the window of the eye. While most adenovirus infections are self-limited, corneal inflammation (keratitis) due to adenovirus can persist or recur for months to years after infection, leading to reduced vision, discomfort, and light sensitivity. Topical corticosteroids effectively suppress late adenovirus keratitis but are associated with vision-threatening side effects. In this short review, we summarize current knowledge on infection of the cornea by adenoviruses, including corneal epithelial cell receptors and determinants of corneal tropism. We briefly discuss mechanisms of stromal keratitis due to adenovirus infection, and review an emerging therapy to mitigate adenovirus corneal infections based on evolving knowledge of corneal epithelial receptor usage.
Collapse
|
4
|
Wu D, Zhang J, Qian T, Dai Y, Mashaghi A, Xu J, Hong J. IFN-γ Regulates the Expression of MICA in Human Corneal Epithelium Through miRNA4448 and NFκB. Front Immunol 2018; 9:1530. [PMID: 30013574 PMCID: PMC6036181 DOI: 10.3389/fimmu.2018.01530] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 06/20/2018] [Indexed: 12/14/2022] Open
Abstract
Purpose Major histocompatibility complex class I-related chain A (MICA), a non-classical major histocompatibility complex molecule, can stimulate or co-stimulate CD8+ T cells or natural killer (nk) cells, thus affecting cornea allograft survival. This study investigated IFN-γ regulation of MICA expression levels in human corneal epithelium by miRNA4448. Methods MICA expression levels in human corneal epithelial cells (HCECs) stimulated with IFN-γ were detected by qRT-PCR and an enzyme-linked immunosorbent assay, and differential miRNA expression levels were measured. qRT-PCR, Western blotting, and immunofluorescence staining revealed nuclear factor kappa B (NFκB)/P65 expression in IFN-γ-treated and miRNA4448-overexpressed HCECs. A luciferase reporter assay was used to predict the interaction between NFκB and MICA. Additionally, HCECs were transfected with MICA plasmid or treated with IFN-γ and NKG2D-mAb and cocultured with NK cells and CD8+ T cells. Cell apoptosis was measured using Annexin V/PI staining. qRT-PCR detected the expression of anti-apoptosis factor Survivin and apoptosis factor Caspase 3 in MICA-transfected and IFN-γ-treated HCECs after co-culturing with NK cells and CD8+ T cells. Results IFN-γ (500 ng/ml, 24 h) upregulated MICA expression in HCECs in vitro. Among six differentially expressed microRNAs, miRNA4448 levels decreased the most after IFN-γ treatment. The overexpression of miRNA4448 decreased MICA expression. miRNA4448 downregulated NFκB/P65 expression in IFN-γ-induced HCEC, and it was determined that NFκB/P65 directly targeted MICA by binding to the promotor region. A coculture with NK cells and CD8+ T cells demonstrated that MICA overexpression enhanced HCEC apoptosis, which could be inhibited by NKG2D-mAb. Simultaneously, Survivin mRNA expression decreased and Caspase3 mRNA expression increased upon the interaction between MICA and NK (CD8+ T) cells in HCECs. Conclusion IFN-γ enhances the expression of MICA in HCECs by modulating miRNA4448 and NFκB/P65 levels, thereby contributing to HCEC apoptosis induced by NK and CD8+ T cells. This discovery may lead to new insights into the pathogenesis of corneal allograft rejection.
Collapse
Affiliation(s)
- Dan Wu
- Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jing Zhang
- Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Tingting Qian
- Department of Immunology and Biotherapy Research Center, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yiqin Dai
- Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Alireza Mashaghi
- Leiden Academic Centre for Drug Research, Faculty of Mathematics and Natural Sciences, Leiden University, Leiden, Netherlands
| | - Jianjiang Xu
- Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jiaxu Hong
- Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,Leiden Academic Centre for Drug Research, Faculty of Mathematics and Natural Sciences, Leiden University, Leiden, Netherlands.,Department of Ophthalmology, The Affiliated Hospital of Guizhou Medical University, Guiyang, China.,Key Laboratory of Myopia, Ministry of Health (Fudan University), Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| |
Collapse
|
5
|
Huang GQ, Yi GG, Wu LW, Feng SF, Wu W, Peng L, Yi RW, Ma W, Lu X. Protective effect of histatin 1 against ultraviolet-induced damage to human corneal epithelial cells. Exp Ther Med 2017; 15:679-684. [PMID: 29399071 PMCID: PMC5772520 DOI: 10.3892/etm.2017.5503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 06/22/2017] [Indexed: 01/18/2023] Open
Abstract
The aim of the present study was to investigate the role of histatin 1 (Hst1) in human corneal epithelial cells (HCECs) exposed to ultraviolet (UV) radiation. Prior to UV irradiation for various durations, HCECs were pre-treated with different concentrations of Hst1 and the effect on cell apoptosis and cell viability were examined by flow cytometry, alamarBlue® and MTT assays to determine the optimal concentration of Hst1 and UV dose. Cells were then subjected to quantitative PCR, ELISA and western blot analysis to determine the expression of cell damage-associated genes. HCECs exposed to UV light for 1 h displayed decreased viability when compared to that of control cells, and a 3 h UV exposure markedly increased the apoptotic rate of HECEs, while apoptosis was inhibited by pre-treatment with Hst1. UV radiation downregulated expression of insulin-like growth factor (IGF)-1 and B-cell lymphoma 2 (Bcl-2), while it upregulated Bcl-2-associated X protein (Bax) expression. Hst1 protected HCECs against UV-induced damage by upregulating the expression of IGF-1 protein and increasing the Bcl-2/Bax ratio. In conclusion, Hst1 may prevent UV-induced damage to corneal epithelial tissue injury and promote its healing.
Collapse
Affiliation(s)
- Guo-Qiang Huang
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.,Department of Ophthalmology, Meizhou People's Hospital, Meizhou, Guangdong 514031, P.R. China
| | - Guo-Guo Yi
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Lai-Wei Wu
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Song-Fu Feng
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Wei Wu
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Ling Peng
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Rui-Wen Yi
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Wenbei Ma
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Xiaohe Lu
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| |
Collapse
|
6
|
Abstract
AIM To evaluate eye irritation potential of palm-based methyl ester sulphonates (MES) of different chain lengths; C12, C14, C16, C16:18. METHODS The Bovine Corneal Opacity and Permeability test method (BCOP), OECD Test Guideline 437, was used as an initial step to study the inducing effect of palm-based MES on irreversible eye damage. The second assessment involved the use of reconstructed human corneal-like epithelium test method, OECD Test Guideline 492 using SkinEthic™ Human Corneal Epithelium to study the potential effect of palm-based MES on eye irritancy. The palm-based MES were prepared in 10% solution (w/v) in deionized water and tested as a liquid and surfactant test substances whereby both test conducted according to the liquid/surfactant treatment protocol. RESULTS The preliminary BCOP results showed that palm-based MES; C12, C14, C16, C16:18 were not classified as severe eye irritants test substances with in vitro irritancy score between 3 and the threshold level of 55. The second evaluation using SkinEthic™ HCE model showed that palm-based MES; C12, C14, C16, C16:18 and three commercial samples were potentially irritants to the eyes with mean tissue viability ≤ 60% and classified as Category 2 according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals. However, there are some limitations of the proposed ocular irritation classification of palm-based MES due to insolubility of long chain MES in 10% solution (w/v) in deionized water. CONCLUSION Therefore, future studies to clarify the eye irritation potential of the palm-based MES will be needed, and could include; methods to improve the test substance solubility, use of test protocol for solids, and/or inclusion of a benchmark anionic surfactant, such as sodium dodecyl sulphate within the study design.
Collapse
Affiliation(s)
- Nor Zuliana Yusof
- a Advanced Oleochemical Technology Division , Malaysian Palm Oil Board , Kajang , Malaysia
| | | | - Zulina Abd Maurad
- a Advanced Oleochemical Technology Division , Malaysian Palm Oil Board , Kajang , Malaysia
| | - Zainab Idris
- a Advanced Oleochemical Technology Division , Malaysian Palm Oil Board , Kajang , Malaysia
| |
Collapse
|
7
|
Abstract
PURPOSE Transforming growth factor-beta (TGF-β) activates the canonical Smad pathway, which includes the Smad family of proteins and SARA (Smad Anchor for Receptor Activation) and other less understood pathways, including one involving p38MAPK. The goal of the current research was to determine if corneal epithelial cells and fibroblasts used the classical or alternative TGF-β-signaling pathways. To examine this question, we made use of Trx-SARA, which inhibits native SARA, thus blocking the Smad pathway. METHODS A human corneal epithelial cell line (HCE-TJ), and stromal fibroblasts (HCF) were infected with retroviruses (RTV) containing either Trx-SARA or Trx-GA (a control plasmid). The effect of Trx-SARA on thrombospondin-1 (TSP-1) expression in both cell types, p15ink4b expression in HCE-TJ, and cellular fibronectin (cFN) expression in HCF was determined. In addition, the effect of p38MAPK inhibitor on TSP-1 and p15ink4b were examined. RESULTS In HCE-TJ with TGF-β1, TSP-1-protein levels increased and peaked at 24 hours. Trx-SARA reduced TSP-1 expression in HCE-TJ, but had no effect on p15ink4b. With HCF, Trx-SARA failed to reduce TSP-1 expression; however, cFN expression decreased and proliferation was inhibited. By blocking the p38MAPK pathway, TSP-1 expression was reduced in HCF and p15ink4b expression was decreased in HCE-TJ. CONCLUSIONS Surprisingly, TSP-1 was regulated through the Smad pathway in HCE-TJ and the p38MAPK pathway in HCF. The p38MAPK pathway also induced p15ink4b in HCE-TJ. Our results indicate that not all TGF-β-target proteins require the Smad pathway, and it may be possible to block certain TGF-β-target proteins without blocking the expression of all the TGF-β-target proteins.
Collapse
Affiliation(s)
- Xiaoqing Guo
- The Schepens Eye Research Institute/Massachusetts Eye and Ear and the Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Audrey E K Hutcheon
- The Schepens Eye Research Institute/Massachusetts Eye and Ear and the Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Jennifer A Tran
- The Schepens Eye Research Institute/Massachusetts Eye and Ear and the Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - James D Zieske
- The Schepens Eye Research Institute/Massachusetts Eye and Ear and the Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
8
|
Jin G, Long C, Liu W, Tang Y, Zhu Y, Zhou X, Ai Y, Zhang Q, Shen H. Identification and characterization of novel alternative splice variants of human SAMD11. Gene 2013; 530:215-21. [PMID: 23978614 DOI: 10.1016/j.gene.2013.08.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 07/30/2013] [Accepted: 08/10/2013] [Indexed: 01/25/2023]
Abstract
Sterile alpha motif domain-containing 11 (SAMD11) is evolutionarily conserved from zebrafish to human. Mouse Samd11 is predominantly expressed in developing retinal photoreceptors and the adult pineal gland, and its transcription is directly regulated by the cone-rod homeodomain protein Crx. However, there has been little research on human SAMD11. To investigate the function of human SAMD11, we first cloned its coding sequence (CDS) and identified up to 45 novel alternative splice variants (ASVs). Mouse Samd11 ASVs were also identified by aligning the mouse Samd11 expressed sequence tags (ESTs) with the annotated sequence. However, the range of expression and transcriptional regulation of SAMD11 differs between human and mouse. Human SAMD11 was found to be widely expressed in many cell lines and ocular tissues and its transcription was not regulated by CRX, OTX2 or NR2E3 proteins. Furthermore, functional analysis indicated that human SAMD11 could promote cell proliferation slightly. In conclusion, this study elucidated the basic characteristics of human SAMD11 and revealed that, although the occurrence of alternative splicing of SAMD11 was conserved, the function of SAMD11 may vary in different species.
Collapse
Affiliation(s)
- Guorong Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Abstract
Background By using a biologically relevant and sensitive three-dimensional model of human corneal epithelium and multiple endpoint analysis, assessment of the potential for eye irritation and long-term compatibility of four registered ophthalmological preparations, ie, Timolabak®, Timoptol®, Nyogel®, and Timogel®, was performed. This approach enables classification of the potential for irritation, discriminating between mildly irritant and non-irritant ocular substances. Methods The exposure protocol included two time periods, ie, 24 hours (acute application) and 72 hours (repeated applications twice daily). This approach allows assessment of not only the acute reaction but also possible recovery, as well as mimicking the potential cumulative effects associated with long-term application. Using benzalkonium chloride (BAK) 0.01% as a positive control, the following parameters were quantified: cellular viability by MTT test, histological analysis by hematoxylin and eosin staining, passive release of interleukin-1α by enzyme-linked immunosorbent assay, and OCLN gene expression by quantitative real-time polymerase chain reaction. Results Cell viability was reduced to under the 50% cutoff value after acute exposure (24 hours) to BAK 0.01%, and after repeated application (72 hours) of Timoptol and Nyogel. Histological analysis after acute exposure showed signs of superficial damage with all formulations, and severe changes after repeated applications of Timoptol, BAK 0.01%, and Nyogel. Timolabak and Timogel did not significantly alter the morphology of the human corneal epithelial cells after the different exposure times. Interleukin-1α release was greater than that for the negative control (>20 pg/mL) and the positive control (BAK 0.01%), Nyogel, and Timoptol treatments and not different after treatment with Timolabak and Timogel. Expression of OCLN, a sign of epithelial barrier impairment, was only significantly upregulated at 24 hours by BAK 0.01%, suggesting a toxic reaction at the ocular surface. OCLN was also overexpressed after repeated application of Nyogel and Timogel. Conclusion Overall, the multiple endpoint analysis approach allows classification of these products according to decreasing order of irritation potential as follows: BAK 0.01%, Timoptol, Nyogel, Timogel, and Timolabak.
Collapse
Affiliation(s)
- Marisa Meloni
- VitroScreen In Vitro Research Laboratories, Milan, Italy
| | | | | |
Collapse
|