1
|
Lightfoot JD, Adams EM, Kamath MM, Wells BL, Fuller KK. Aspergillus fumigatus Hypoxia Adaptation Is Critical for the Establishment of Fungal Keratitis. Invest Ophthalmol Vis Sci 2024; 65:31. [PMID: 38635243 PMCID: PMC11044834 DOI: 10.1167/iovs.65.4.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/15/2024] [Indexed: 04/19/2024] Open
Abstract
Purpose The poor visual outcomes associated with fungal keratitis (FK) underscore a need to identify fungal pathways that can serve as novel antifungal targets. In this report, we investigated whether hypoxia develops in the FK cornea and, by extension, if fungal hypoxia adaptation is essential for virulence in this setting. Methods C57BL/6J mice were inoculated with Aspergillus fumigatus and Fusarium solani var. petroliphilum via topical overlay or intrastromal injection. At various time points post-inoculation (p.i.), animals were injected with pimonidazole for the detection of tissue hypoxia through immunofluorescence imaging. The A. fumigatus srbA gene was deleted through Cas9-mediated homologous recombination and its virulence was assessed in the topical infection model using slit-lamp microscopy and optical coherence tomography (OCT). Results Topical inoculation with A. fumigatus resulted in diffuse pimonidazole staining across the epithelial and endothelial layers within 6 hours. Stromal hypoxia was evident by 48 hours p.i., which corresponded to leukocytic infiltration. Intrastromal inoculation with either A. fumigatus or F. solani similarly led to diffuse staining patterns across all corneal cell layers. The A. fumigatus srbA deletion mutant was unable to grow at oxygen levels below 3% in vitro, and corneas inoculated with the mutant failed to develop signs of corneal opacification, inflammation, or fungal burden. Conclusions These results suggest that fungal antigen rapidly drives the development of corneal hypoxia, thus rendering fungal SrbA or related pathways essential for the establishment of infection. Such pathways may therefore serve as targets for novel antifungal intervention.
Collapse
Affiliation(s)
- Jorge D. Lightfoot
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Emily M. Adams
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Manali M. Kamath
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Becca L. Wells
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Kevin K. Fuller
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| |
Collapse
|
2
|
Priyadarsini S, McKay TB, Escandon P, Nicholas SE, Ma JX, Karamichos D. Cell sheet-based approach to study the diabetic corneal stroma. Exp Eye Res 2023; 237:109717. [PMID: 37944849 DOI: 10.1016/j.exer.2023.109717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/24/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
Prolonged hyperglycemia during diabetes mellitus (DM) is associated with severe complications that may affect both the anterior and posterior ocular segments, leading to impaired vision or blindness. The cornea is a vital part of the eye that has a dual role as a protective transparent barrier and as a major refractive structure and is likewise negatively affected by hyperglycemia in DM. Understanding the cellular and molecular mechanisms underlying the phenotypic changes associated with DM is critical to developing targeted therapies to promote tissue integrity. In this proof-of-concept study, we applied a cell sheet-based approach to generate stacked constructs of physiological corneal thickness using primary human corneal fibroblasts isolated from cadaveric control (healthy), Type 1 DM and Type 2 DM corneal tissues. Self-assembled corneal stromal sheets were generated after 2 weeks in culture, isolated, and subsequently assembled to create stacked constructs, which were evaluated using transmission electron microscopy. Analysis of gene expression patterns revealed significant downregulation of fibrotic markers, α-smooth muscle actin, and collagen type 3, with stacking in Type 2 DM constructs when compared to controls. IGF1 expression was significantly upregulated in Type 2 DM constructs compared to controls with a significant reduction induced by stacking. This study describes the development of a thicker, self-assembled corneal stromal construct as a platform to evaluate phenotypic differences associated with DM-derived corneal fibroblasts and enable the development of targeted therapeutics to promote corneal integrity.
Collapse
Affiliation(s)
- Shrestha Priyadarsini
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Tina B McKay
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Paulina Escandon
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Sarah E Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Jian-Xing Ma
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC, 27101, USA
| | - Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
| |
Collapse
|
3
|
Tang H, Huang L, Hu J. Inhibition of the m6A Methyltransferase METTL3 Attenuates the Inflammatory Response in Fusarium solani-Induced Keratitis via the NF-κB Signaling Pathway. Invest Ophthalmol Vis Sci 2022; 63:2. [PMID: 36194423 PMCID: PMC9547362 DOI: 10.1167/iovs.63.11.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to elucidate the effect of methyltransferase-like enzyme 3 (METTL3) on inflammation and the NF-κB signaling pathway in fungal keratitis (FK). Methods We established corneal stromal cell models and FK mouse models by incubation with Fusarium solani. The overall RNA N6-methyladenosine (m6A) level was determined using an m6A RNA methylation assay kit. The expression of METTL3 was quantified via real-time quantitative polymerase chain reaction (RT–PCR), Western blotting, and immunofluorescence. Subsequently, the level of tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) was identified by Western blotting and immunofluorescence. Moreover, we assessed the effect of METTL3 by transfecting cells with siRNA (in vitro) or adeno-associated virus (in vivo). Hematoxylin and eosin (H&E) staining and slit-lamp biomicroscopy were performed to evaluate corneal damage. Furthermore, the state of NF-κB signaling pathway activation was examined by Western blotting. In addition, RT–PCR and enzyme-linked immunosorbent assays (ELISAs) were performed to evaluate levels of the pro-inflammatory factors interleukin-1β (IL-1β), interleukin-6 (IL-6) and TNF-ɑ. Results Our data demonstrated that the levels of the RNA m6A methylation and METTL3 were dramatically increased and that the NF-κB signaling pathway was activated in Fusarium solani-induced keratitis. Inhibition of METTL3 decreased the level of TRAF6, downregulated the phospho-p65(p-p65)/p65 and phospho-IκB(p-IκB)/IκB protein ratios, simultaneously attenuating the inflammatory response and fungal burden in FK. Conclusions Our research suggests that the m6A methyltransferase METTL3 regulates the inflammatory response in FK by modulating the NF-κB signaling pathway.
Collapse
Affiliation(s)
- Hanfeng Tang
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
| | - Liwei Huang
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
| | - Jianzhang Hu
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
| |
Collapse
|