Abstract

PurposeTo 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. MethodTREM-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.ResultsTREM-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.ConclusionsFK506 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.

Highlights

  • Fungal keratitis is a sight-threatening ocular disease with a growing incidence, especially in developing countries [1]

  • triggering receptor expressed on myeloid cells-1 (TREM-1) expression was higher in the corneas of fungal keratitis patients than in normal human corneas

  • TREM-1 expression was detected in fungus-infected corneas and normal human corneas to determine whether TREM-1 induces corneal inflammation

Read more

Summary

Introduction

Fungal keratitis is a sight-threatening ocular disease with a growing incidence, especially in developing countries [1]. Neutrophils are active inflammatory immune cells in innate immunity, quickly arriving at a lesion to eliminate fungi at an early stage [3]. Many studies have confirmed that macrophages play an important role, mediating the acquired immune response to eradicate infection [4], usually at a later stage of infection. Excessive inflammation due to adaptive immunity and innate immunity can cause tissue damage and even life-threatening consequences. Inflammation is likely one of the most important causes of corneal destruction after fungal infection because infected corneas often undergo a serious suppurative process [5]. A test for myeloperoxidase (MPO) protein was used to detect infiltrating neutrophils over the short time course of an Aspergillus fumigatus-induced keratitis model.

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call