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Fang X, Lian H, Bi S, Liu S, Yuan X, Liao C. Roles of pattern recognition receptors in response to fungal keratitis. Life Sci 2022; 307:120881. [PMID: 35963303 DOI: 10.1016/j.lfs.2022.120881] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/31/2022] [Accepted: 08/08/2022] [Indexed: 11/29/2022]
Abstract
Fungal keratitis is one of the leading causes of blindness worldwide, which has become an increasingly serious threat to public ocular health, but no effective treatment strategies are available now. Pattern recognition receptors (PRRs) of the innate immune system are the first line of host defense against fungal infections. They could recognize pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) and trigger an array of inflammatory responses. Over the last decades, research has resulted in significant progress regarding the roles of PRRs in fungal keratitis. This review will highlight the importance of several pattern recognition receptors (C-type lectin-like receptors, Toll-like receptors, and NOD-like receptors) in regulating the innate immunity under fungal keratitis and describe the crosstalk and collaboration in PRRs contributing to disease pathology. Meanwhile, some potential therapy-based PRRs against corneal fungal infections are discussed.
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Affiliation(s)
- Xiaolong Fang
- The School of Medicine, Nankai University, Tianjin 300071, China; Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin 300020, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Huifang Lian
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China; Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin 300020, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Ophthalmology, Baoding First Central Hospital, Baoding, Hebei 071000, China
| | - Shihao Bi
- Neck-Shoulder and Lumbocrural Pain Hospital of Shandong First Medical University, Shandong First Medical University, Shandong Academy of Medical Sciences, Jinan, Shandong 250062, China
| | - Sijin Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xiaoyong Yuan
- The School of Medicine, Nankai University, Tianjin 300071, China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China; Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin 300020, China.
| | - Chunyang Liao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Lian H, Fang X, Li Q, Liu S, Wei Q, Hua X, Li W, Liao C, Yuan X. NLRP3 Inflammasome-Mediated Pyroptosis Pathway Contributes to the Pathogenesis of Candida albicans Keratitis. Front Med (Lausanne) 2022; 9:845129. [PMID: 35463001 PMCID: PMC9020473 DOI: 10.3389/fmed.2022.845129] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/03/2022] [Indexed: 02/03/2023] Open
Abstract
Purpose Fungal keratitis is a sight-threatening corneal infection caused by fungal pathogens, and the pathogenic mechanisms have not been fully elucidated. The aim of this study was to determine whether NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis contributes to Candida albicans (C. albicans) keratitis and explore the underlying mechanism. Methods An in vivo mouse model of C. albicans keratitis and an in vitro culture model of human corneal epithelial cells (HCECs) challenged with heat-killed C. albicans (HKCA) were established in this study. The degree of corneal infection was evaluated by clinical scoring. Gene expression was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis or immunofluorescence staining was performed to evaluate protein expression. TdT-mediated dUTP nick end labeling (TUNEL) staining was performed to examine the pyroptotic cell death. A lactate dehydrogenase (LDH) release assay was performed to assess cytotoxicity. Results Compared with the mock-infected group, we observed that the mRNA levels of NLRP3, caspase-1 (CASP1), interleukin (IL)−1β and gasdermin-D (GSDMD) in C. albicans-infected mice cornea was significantly increased. Our data also demonstrated that the protein expression of NLRP3 and the pyroptosis-related markers apoptosis-associated speck-like protein containing a CARD (ASC), cleaved CASP1, N-GSDMD, cleaved IL-1β and cleaved IL-18 as well as pyroptotic cell death were dramatically elevated in the mouse model of C. albicans keratitis. More importantly, NLRP3 knockdown markedly alleviated pyroptosis and consequently reduced corneal inflammatory reaction in C. albicans keratitis. In vitro, the presence of activated NLRP3 inflammasome and pyroptotic cell death were validated in HCECs exposed to HKCA. Furthermore, the potassium (K+) channel inhibitor glyburide decreased LDH release and suppressed NLRP3 inflammasome activation and pyroptosis in HCECs exposed to HKCA. Conclusion In conclusion, the current study revealed for the first time that NLRP3 inflammasome activation and pyroptosis occur in C. albicans-infected mouse corneas and HCECs. Moreover, NLRP3 inflammasome-mediated pyroptosis signaling is involved in the disease severity of C. albicans keratitis. Therefore, This NLRP3 inflammasome-dependent pathway may be an attractive target for the treatment of fungal keratitis.
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Affiliation(s)
- Huifang Lian
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China.,Department of Ophthalmology, Baoding First Central Hospital, Baoding, China.,State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - XiaoLong Fang
- Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China.,State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.,The School of Medicine, Nankai University, Tianjin, China
| | - Qingyu Li
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China
| | - Shuang Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qiuhong Wei
- Department of Ophthalmology, Baoding First Central Hospital, Baoding, China
| | - Xia Hua
- Aier Eye Hospital, Tianjin, China
| | - Wenguang Li
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Chunyang Liao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Xiaoyong Yuan
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China.,The School of Medicine, Nankai University, Tianjin, China
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Experimental Models for Fungal Keratitis: An Overview of Principles and Protocols. Cells 2020; 9:cells9071713. [PMID: 32708830 PMCID: PMC7408389 DOI: 10.3390/cells9071713] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 12/21/2022] Open
Abstract
Fungal keratitis is a potentially blinding infection of the cornea that afflicts diverse patient populations worldwide. The development of better treatment options requires a more thorough understanding of both microbial and host determinants of pathology, and a spectrum of experimental models have been developed toward this end. In vivo (animal) models most accurately capture complex pathological outcomes, but protocols may be challenging to implement and vary widely across research groups. In vitro models allow for the molecular dissection of specific host cell–fungal interactions, but they do so without the appropriate environmental/structural context; ex vivo (corneal explant) models provide the benefits of intact corneal tissue, but they do not provide certain pathological features, such as inflammation. In this review, we endeavor to outline the key features of these experimental models as well as describe key technical variations that could impact study design and outcomes.
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