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Liu R, Tu M, Xue J, Xiao B, Li J, Liang L. Oleic acid induces lipogenesis and NLRP3 inflammasome activation in organotypic mouse meibomian gland and human meibomian gland epithelial cells. Exp Eye Res 2024; 241:109851. [PMID: 38453039 DOI: 10.1016/j.exer.2024.109851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/09/2024]
Abstract
The accumulation of oleic acid (OA) in the meibum from patients with meibomian gland dysfunction (MGD) suggests that it may contribute to meibomian gland (MG) functional disorder, as it is a potent stimulator of acne-related lipogenesis and inflammation in sebaceous gland. Therefore, we investigate whether OA induces lipogenesis and inflammasome activation in organotypic cultured mouse MG and human meibomian gland epithelial cells (HMGECs). Organotypic cultured mouse MG and HMGECs were exposed to OA or combinations with specific AMPK agonists 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR). Lipogenic status, ductal keratinization, squamous metaplasia, NLRP3/ASC/Caspase-1 inflammasome activation, proinflammatory cytokine IL-1β production, and AMPK pathway phosphorylation in MG were subsequently examined by lipid staining, immunofluorescence staining, immunohistochemical staining, ELISA assay, and Western blot analyses. We found that OA significantly induced lipid accumulation, ductal keratinization, and squamous metaplasia in organotypic cultured MG, as evidenced by increased lipids deposition within acini and duct, upregulated expression of lipogenic proteins (SREBP-1 and HMGCR), and elevation of K10/Sprr1b. Additionally, OA induced NLRP3/ASC/Caspase-1 inflammasome activation, cleavage of Caspase-1, and production of downstream proinflammatory cytokine IL-1β. The findings of lipogenesis and NLRP3-related proinflammatory response in OA-stimulated HMGECs were consistent with those in organotypic cultured MG. OA exposure downregulated phospho-AMPK in two models, while AICAR treatment alleviated lipogenesis by improving AMPK/ACC phosphorylation and SREBP-1/HMGCR expression. Furthermore, AMPK amelioration inhibited activation of the NLRP3/ASC/Caspase-1 axis and secretion of IL-1β, thereby relieving the OA-induced proinflammatory response. These results demonstrated that OA induced lipogenic disorder and NLRP3 inflammasome activation in organotypic cultured mouse MG and HMGECs by suppressing the AMPK signaling pathway, indicating OA may play an etiological role in MGD.
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Affiliation(s)
- Ren Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Mengqian Tu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Jianwen Xue
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Bing Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Jing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
| | - Lingyi Liang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
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Sprogyte L, Park M, Di Girolamo N. Pathogenesis of Alkali Injury-Induced Limbal Stem Cell Deficiency: A Literature Survey of Animal Models. Cells 2023; 12:cells12091294. [PMID: 37174694 PMCID: PMC10177508 DOI: 10.3390/cells12091294] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/28/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
Limbal stem cell deficiency (LSCD) is a debilitating ocular surface disease that eventuates from a depleted or dysfunctional limbal epithelial stem cell (LESC) pool, resulting in corneal epithelial failure and blindness. The leading cause of LSCD is a chemical burn, with alkali substances being the most common inciting agents. Characteristic features of alkali-induced LSCD include corneal conjunctivalization, inflammation, neovascularization and fibrosis. Over the past decades, animal models of corneal alkali burn and alkali-induced LSCD have been instrumental in improving our understanding of the pathophysiological mechanisms responsible for disease development. Through these paradigms, important insights have been gained with regards to signaling pathways that drive inflammation, neovascularization and fibrosis, including NF-κB, ERK, p38 MAPK, JNK, STAT3, PI3K/AKT, mTOR and WNT/β-catenin cascades. Nonetheless, the molecular and cellular events that underpin re-epithelialization and those that govern long-term epithelial behavior are poorly understood. This review provides an overview of the current mechanistic insights into the pathophysiology of alkali-induced LSCD. Moreover, we highlight limitations regarding existing animal models and knowledge gaps which, if addressed, would facilitate development of more efficacious therapeutic strategies for patients with alkali-induced LSCD.
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Affiliation(s)
- Lina Sprogyte
- Mechanisms of Disease and Translational Research, School of Biomedical Sciences, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Mijeong Park
- Mechanisms of Disease and Translational Research, School of Biomedical Sciences, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Nick Di Girolamo
- Mechanisms of Disease and Translational Research, School of Biomedical Sciences, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2052, Australia
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Xu J, Chen P, Luan X, Yuan X, Wei S, Li Y, Guo C, Wu X, Di G. The NLRP3 Activation in Infiltrating Macrophages Contributes to Corneal Fibrosis by Inducing TGF-β1 Expression in the Corneal Epithelium. Invest Ophthalmol Vis Sci 2022; 63:15. [PMID: 35838447 PMCID: PMC9296889 DOI: 10.1167/iovs.63.8.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Purpose To explore the effect and mechanism of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes on corneal fibrosis. Methods The wild-type, NLRP3 knockout (KO), and myeloid cell-specific NLRP3 KO (NLRP3 Lyz-KO) C57 mice were used to establish a corneal scarring model. NLRP3 inhibitor, IL-1β neutralizing antibody, and an IL-1R antagonist were used to investigate the role of NLRP3 and IL-1β in corneal fibrosis. The expression of the NLRP3 signaling pathway related proteins, alpha-smooth muscle actin, TGF-β was determined by quantitative real-time polymerase chain reaction, Western blotting, and immunofluorescence staining. Flow cytometry was used to detect the infiltration of macrophages during corneal fibrosis. Results The components of the NLRP3 inflammasomes were elevated and activated during corneal scarring. Additionally, genetic or chemical-mediated blocking of NLRP3 as well as IL-1β significantly alleviated corneal fibrosis. Moreover, neutrophil (CD45+Ly6G+) and macrophage (CD45+ F4/80+) accumulation increased in the cornea during the progression of corneal fibrosis. Intriguingly, the increased concentrations of NLRP3 and IL-1β were prominently colocalized with the infiltrating F4/80+ macrophages. Expectedly, NLRP3 Lyz-KO mice exhibited a marked decrease in their corneal fibrosis symptoms. Mechanistically, the activation of IL-1β or macrophage NLRP3 stimulated the expression of TGF-β1 in the corneal epithelial cells, whereas an NLRP3 deficiency decreased its expression in the corneal epithelium. Conclusions These observations revealed that the NLRP3 inflammasome activation in infiltrating macrophages contributes to corneal fibrosis by regulating corneal epithelial TGF-β1 expression. Targeting the NLRP3 inflammasome might be a promising strategy for the treatment of corneal scarring.
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Affiliation(s)
- Jing Xu
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Peng Chen
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Xiaoyu Luan
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Xinying Yuan
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Susu Wei
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Yaxin Li
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
| | - Chuanlong Guo
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Xianggen Wu
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Guohu Di
- School of Basic Medicine, Medical College, Qingdao University, Qingdao, China
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Nuwormegbe S, Park NY, Kim SW. Lobeglitazone attenuates fibrosis in corneal fibroblasts by interrupting TGF-beta-mediated Smad signaling. Graefes Arch Clin Exp Ophthalmol 2021; 260:149-162. [PMID: 34468828 DOI: 10.1007/s00417-021-05370-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/30/2021] [Accepted: 08/06/2021] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Transforming growth factor beta 1 (TGF-β1) is an important cytokine released after ocular surface injury to promote wound healing. However, its persistence at the injury site triggers a fibrotic response that leads to corneal scarring and opacity. Thiazolidinediones (TZDs) are synthetic peroxisome proliferator-activated receptor gamma (PPAR-γ) ligands used to regulate glucose and lipid metabolism in the management of type 2 diabetes. Studies have also showed TZDs have antifibrotic effect. In this study, we investigated the antifibrotic effect of the TZD lobeglitazone on TGF-β1-induced fibrosis in corneal fibroblasts. METHODS Human primary corneal fibroblasts were cultivated and treated with TGF-β1 (5 ng/mL) to induce fibrosis, with or without pre-treatments with different concentrations of lobeglitazone. Myofibroblast differentiation and extracellular matrix (ECM) protein expression was evaluated by western blotting, immunofluorescence, real-time PCR, and collagen gel contraction assay. The effect of lobeglitazone on TGF-β1-induced reactive oxygen species (ROS) generation was evaluated by DCFDA-cellular ROS detection assay kit. Signaling proteins were evaluated by western blotting to determine the mechanism underlying the antifibrotic effect. RESULTS Our results showed lobeglitazone attenuated TGF-β1-induced ECM synthesis and myofibroblast differentiation of corneal fibroblasts. This antifibrotic effect appeared to be independent of PPAR signaling and rather due to the inhibition of the TGF-β1-induced Smad signaling. Lobeglitazone also blocked TGF-β1-induced ROS generation and nicotinamide adenine dinucleotide phosphate oxidase (Nox) 4 transcription. CONCLUSION These findings indicate that lobeglitazone may be a promising therapeutic agent for corneal scarring. KEY MESSAGES.
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Affiliation(s)
- Selikem Nuwormegbe
- Department of Global Medical Science, Wonju College of Medicine, Yonsei University, Wonju, Ilsan-ro, Gangwon-do, 26426, Republic of Korea
| | - Na-Young Park
- Department of Ophthalmology, Wonju College of Medicine, Yonsei University, Wonju, Ilsan-ro, Gangwon-do, 26426, Republic of Korea
| | - Sun Woong Kim
- Department of Ophthalmology, Wonju College of Medicine, Yonsei University, Wonju, Ilsan-ro, Gangwon-do, 26426, Republic of Korea.
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Liao K, Cui Z, Zeng Y, Liu J, Wang Y, Wang Z, Tang S, Chen J. Inhibition of enhancer of zeste homolog 2 prevents corneal myofibroblast transformation in vitro. Exp Eye Res 2021; 208:108611. [PMID: 33992624 DOI: 10.1016/j.exer.2021.108611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 04/25/2021] [Accepted: 04/29/2021] [Indexed: 12/18/2022]
Abstract
PURPOSE Corneal fibroblast can be transformed into corneal myofibroblasts by TGF-β1. Enhancer of zeste homolog 2 (EZH2) upregulation has been observed in the occurrence of other fibrotic disorders. We investigated the role of EZH2 in the progression of corneal fibrosis and the antifibrotic effect of EZH2 inhibition in corneal fibroblasts (CFs). METHODS Primary CFs were isolated from corneal limbi and the CFs were treated with TGF-β1 to induce fibrosis. EPZ-6438 and EZH2 siRNA were used to inhibit EZH2 expression. Myofibroblast activation and extracellular matrix (ECM) protein synthesis was detected by quantitative real-time PCR, western blotting, and immunofluorescence staining assay. The functions of myofibroblast were evaluated by cell migration and collagen gel contraction assays. Molecular mechanisms involved in EZH2 inhibition were investigated by RNA sequencing. RESULTS TGF-β1 activated EZH2 expression in CFs. Treatment with EPZ-6438 (5 μM) and EZH2 siRNA considerably suppressed corneal myofibroblast activation and ECM protein synthesis in CFs induced by TGF-β1 when compared to the control group. EPZ-6438 (5 μM) suppressed cell migration and gel contraction in CFs. RNA sequencing results revealed that antifibrotic genes were activated after EZH2 inhibition to suppress corneal myofibroblast activation. CONCLUSION Inhibition of EZH2 suppresses corneal myofibroblast activation and ECM protein synthesis, and could serve as a novel therapeutic target for preventing corneal scarring.
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Affiliation(s)
- Kai Liao
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China; Aier Eye Institute, Changsha, Hunan Province, China
| | - Zekai Cui
- Aier Eye Institute, Changsha, Hunan Province, China
| | - Yong Zeng
- Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
| | - Jian Liu
- Aier Eye Institute, Changsha, Hunan Province, China
| | - Yini Wang
- Aier Eye Institute, Changsha, Hunan Province, China
| | - Zhijie Wang
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China; Aier Eye Institute, Changsha, Hunan Province, China
| | - Shibo Tang
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China; Aier Eye Institute, Changsha, Hunan Province, China; CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
| | - Jiansu Chen
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China; Aier Eye Institute, Changsha, Hunan Province, China; Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.
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