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Protective role for CD1d-reactive invariant natural killer T cells in cauterization-induced corneal inflammation
Toru Oshima1, Koh-Hei Sonoda, Shintaro Nakao
1Department of Ophthalmology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, Japan.
Purpose:
Corneal inflammation can be induced by various stimuli, such as chemical burns, trauma, and acute bacterial infection, and directly impairs visual acuity. Natural killer T (NKT) cells belong to a specialized population of leukocytes that coexpress the T-cell receptor and NK markers. This study examined the role of CD1d-reactive invariant NKT cells in cauterization-induced acute corneal inflammation.
Methods:
The corneas of CD1d-knockout (KO) mice and Jalpha18-KO mice (both of which are NKT cell deficient) and control mice were cauterized with silver nitrate. Corneal edema and opacity were examined, and the phenotypes of the corneal-infiltrating cells were analyzed histologically at 24 hours and by flow cytometry at 96 hours. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the expression of vascular endothelial growth factor (VEGF), interferon (IFN)gamma, and tumor necrosis factor (TNF)alpha in the cauterized corneas.
Results:
The CD1d-KO and Jalpha18-KO mice had significantly greater levels of corneal edema and opacity than did the control mice. Although the number of infiltrating cells was not significantly different at 96 hours, both groups of NKT cell-deficient mice demonstrated increased early neutrophil accumulation at 24 hours and early expression of VEGF, IFNgamma, and TNFalpha. There was no difference in the level of VEGF-induced corneal neovascularization.
Conclusions:
NKT cells appear to regulate the early accumulation of neutrophils, protect the cornea from excessive inflammation, and maintain corneal clarity. However, in this study, they did not affect the corneal revascularization process induced by VEGF.
Insights
Natural killer T (NKT) cells protect the cornea from inflammation and maintain clarity by regulating neutrophil accumulation. These specialized immune cells are crucial for corneal health following injury.
Area of Science:
- Immunology
- Ophthalmology
Background:
- Corneal inflammation impairs vision and can result from burns, trauma, or infection.
- Natural killer T (NKT) cells are specialized leukocytes with roles in immunity.
Purpose of the Study:
- To investigate the function of CD1d-reactive invariant NKT cells in acute corneal inflammation induced by cauterization.
- To understand the protective role of NKT cells in maintaining corneal clarity and visual function.
Main Methods:
- Utilized CD1d-knockout and Jalpha18-knockout mice (NKT cell deficient) and control mice.
- Induced corneal inflammation via silver nitrate cauterization.
- Assessed corneal edema, opacity, cellular infiltration, and gene expression (VEGF, IFNγ, TNFα).
Main Results:
- NKT cell-deficient mice exhibited significantly increased corneal edema and opacity.
- Early neutrophil accumulation and expression of VEGF, IFNγ, and TNFα were elevated in NKT cell-deficient mice.
- Corneal neovascularization induced by VEGF was not affected by NKT cell deficiency.
Conclusions:
- NKT cells play a regulatory role in early neutrophil influx during corneal inflammation.
- NKT cells contribute to maintaining corneal clarity and preventing excessive inflammation.
- NKT cells do not appear to influence VEGF-driven corneal revascularization.
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