Scleral Proteome in Noninfectious Scleritis Unravels Upregulation of Filaggrin-2 and Signs of Neovascularization

• Published in: Investigative ophthalmology & visual science 2023-03, Vol.64 (3), p.27-27
• Main Authors: Vergouwen, Daphne P C, Ten Berge, Josianne C, Guzel, Coskun, van den Bosch, Thierry P P, Verdijk, Robert M, Rothova, Aniki, Luider, Theo M, Schreurs, Marco W J
• Format: Article
• Language: English
• Subjects: Filaggrin Proteins; Humans; Immunology and Microbiology; Myosins - metabolism; Proteome - metabolism; Sclera - metabolism; Scleritis - diagnosis; Up-Regulation
• ISSN: 1552-5783; 0146-0404; 1552-5783
• DOI: 10.1167/iovs.64.3.27

Scleritis is a severe inflammatory ocular disorder with unknown pathogenesis. We investigated healthy sclera as well as sclera affected by noninfectious scleritis for differentially expressed proteins using a mass spectrometry approach. We collected scleral samples of enucleated eyes due to severe noninfectious scleritis (n = 3), and control scleral tissues (n = 5), all exenterated eyes for eyelid carcinomas (n = 4), or choroidal melanoma (n = 1) without scleral invasion. Samples were prepared for the nano liquid-chromatography mass spectrometer (LC-MS), data were analyzed using proteomics software (Scaffold), and is available via ProteomeXchange (identifier PXD038727). Samples were also stained for immuno-histopathological evaluation. Mass spectrometry identified 629 proteins within the healthy and diseased scleral tissues, whereof collagen type XII, VI, and I were the most abundantly expressed protein. Collagen type II-XII was also present. Filaggrin-2, a protein that plays a crucial role in epidermal barrier function, was found upregulated in all scleritis cases. In addition, other epithelial associated proteins were upregulated (such as keratin 33b, 34, and 85, epiplakin, transglutaminase-3, galectin 7, and caspase-14) in scleritis. Further, upregulated proteins involved in regulation of the cytoskeleton (vinculin and myosin 9), and housekeeping proteins were found (elongation factor-2 and cytoplasmic dynein 1) in our study. Upregulation of filaggrin-2 and myosin-9 was confirmed with immunohistochemistry, the latter protein showing co-localization with the endothelial cell marker ETC-related gene (ERG), indicating neovascularization in scleral tissue affected by scleritis. We found upregulation of filaggrin-2 and signs of neovascularization in scleral tissue of patients with noninfectious scleritis. Further research, ideally including more scleritis cases, is needed to validate our findings.