Tripartite Motif 8 (TRIM8) Positively Regulates Pro-inflammatory Responses in Pseudomonas aeruginosa-Induced Keratitis Through Promoting K63-Linked Polyubiquitination of TAK1 Protein

Pseudomonas aeruginosa (PA)-induced keratitis is a rapidly progressive ocular infectious disease that often leads to inflammatory epithelial edema, stromal infiltration, tissue destruction, corneal ulceration, and vision loss. In this study, we investigate the role of tripartite motif 8 (TRIM8) in regulating the inflammatory process of PA-induced keratitis. The expression of TRIM8 was increased in mouse corneas and in vitro-cultured macrophages after PA infection. Knockdown of the expression of TRIM8 significantly inhibited the activation of NF-kappa B signaling and decreased the production of proinflammatory cytokines both in vivo and in vitro after infected with PA. Furthermore, we investigated the potential mechanism and we found after PA infection that TRIM8 could promote K63-linked poly-ubiquitination of transforming growth factor beta-activated kinase 1 (TAK1), leading to the activation of TAK1 and enhanced inflammatory responses. Taken together, we demonstrated that TRIM8 has proinflammatory effect on PA-induced keratitis and suggest TRIM8 as a potential therapeutic target for keratitis.