title: Tacrolimus (FK506) suppresses TREM-1 expression at an early but not at a late stage in a murine model of fungal keratitis.
abstract: OBJECTIVE
  To investigate the efficacy and mechanism of tacrolimus(FK506), which is a novel macrolide immunosuppressant, in inhibiting triggering receptor expressed on myeloid cells-1 (TREM-1) expression in a murine keratitis model induced by Aspergillus fumigatus.
  
  
  METHODS
  TREM-1 was detected in 11 fungus-infected human corneas by quantitative real-time PCR (qRT-PCR). RAW264.7 macrophages were divided into four groups, which received treatment with zymosan (100 µg/ml), zymosan (100 µg/ml) + mTREM-1/Fc protein (1 µg/ml), or zymosan (100 µg/ml) + FK506 (20 µM) or negative-control treatment. After this treatment, the expression of TREM-1, interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) was assayed using qRT-PCR and ELISA. The mouse model of fungal keratitis was created by intrastromal injection with Aspergillus fumigatus, and the mice were divided into 2 groups: group A received vehicle eye drops 4 times each day, and group B received 4 doses of FK506 eye drops each day. Corneal damage was evaluated by clinical scoring and histologic examination,and myeloperoxidase (MPO) protein levels were also detected by ELISA. The expression of TREM-1, IL-1β and TNFα was then determined at different time points using qRT-PCR and ELISA.
  
  
  RESULTS
  TREM-1 expression dramatically increased in the human corneas with fungal keratitis. In contrast, FK506 reduced the expression of TREM-1, IL-1β and TNFα in RAW264.7 macrophages stimulated with zymosan. In the mouse model, at day 1 post-infection, the corneal score of the FK506-treated group was lower than that of the control, and polymorphonuclear neutrophil (PMN) infiltration was diminished. TREM-1, IL-1β and TNFα expression was significantly reduced at the same time point. However, the statistically significant differences in cytokine expression, clinical scores and infiltration disappeared at 5 days post-infection.
  
  
  CONCLUSIONS
  FK506 may inhibit the inflammation induced by fungi and alleviate the severity of corneal damage at an early stage of fungal keratitis by downregulating TREM-1 expression.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China; Physical Examination Center, The Third Affiliated Hospital of Sun Yat-Sen University-Lingnan Hospital, Guangzhou, China.
authors.forename: Weilan
authors.initials: W
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Shiqi
authors.initials: S
authors.lastname: Ling
authors.affiliation: Department of Ophthalmology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Xiuhua
authors.initials: X
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Binwu
authors.initials: B
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center of Sun Yat-sen University, Guangzhou, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Yuan
mesh_terms: D000818:Animals; D001232:Aspergillus fumigatus / Q000302:isolation & purification; D002460:Cell Line; D003315:Cornea / Q000382:microbiology; D003881:Dermatomycoses / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D011971:Receptors, Immunologic / Q000378:metabolism*; D016559:Tacrolimus / Q000627:therapeutic use*; D000073871:Triggering Receptor Expressed on Myeloid Cells-1
chemical_list: D007166:Immunosuppressive Agents; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C517262:TREM1 protein, mouse; D000073871:Triggering Receptor Expressed on Myeloid Cells-1; D016559:Tacrolimus