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Immunohistochemical evaluation of murine HSV-1 keratouveitis
H M Wang1, M M Sheu, R D Stulting
1Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322.
Abstract:
The intraocular inflammatory reaction in a murine model of herpes simplex keratouveitis was studied using immunohistochemical techniques. 5 x 10(5) PFU of HSV-1 (Stewart strain) was applied to the abraded cornea of BALB/c mice. The subsequent development of keratouveitis was documented by sequential examination, conventional histology and immunohistochemical staining of frozen sections with the following monoclonal antibodies: Thy-1, Lyt-1, Lyt-2, Ia, Mac-1 and Lyb-8.2. At one week (in the early stage) there was moderate central corneal edema with inflammatory cell infiltration, consisting of a predominance of polymorphonuclear leukocytes, with the appearance of helper/inducer T-cells(Th/i). At two weeks (in the middle stage), a geographic corneal ulcer developed and the majority of inflammatory cells were still polymorphonuclear leukocytes. However, there was a further increase in the Th/i cell population, with the first appearance of B-cells. At three weeks (in the late stage), a dense stromal corneal scar was observed and there was a decrease in the inflammatory cell population, with the predominant cell being the B-cell. Throughout the evolution of HSV-1 keratouveitis, a mild inflammatory reaction was observed in the uvea. However, the number of inflammatory cells present was too small to allow more definitive characterization. Patchy Ia staining which is noted in the normal choroid increased markedly throughout the keratouveitis.
Insights
This study tracked immune cells during herpes simplex virus (HSV-1) induced eye inflammation in mice. B-cells became dominant in later stages, indicating a shift in the immune response to this viral eye infection.
Area of Science:
- Ophthalmology
- Immunology
- Virology
Background:
- Herpes simplex virus (HSV-1) is a common cause of infectious blindness.
- Understanding the immune response in herpes simplex keratouveitis (HSK) is crucial for developing effective treatments.
- Murine models are essential for studying the pathogenesis of HSK.
Purpose of the Study:
- To investigate the intraocular inflammatory cell dynamics during experimental HSV-1 keratouveitis in a murine model.
- To characterize the sequential infiltration and changes in immune cell populations within the cornea and uvea.
Main Methods:
- Induction of HSV-1 keratouveitis in BALB/c mice using topical application of HSV-1.
- Sequential examination, conventional histology, and immunohistochemical staining of corneal and uveal tissues.
- Use of monoclonal antibodies (Thy-1, Lyt-1, Lyt-2, Ia, Mac-1, Lyb-8.2) to identify specific immune cell populations (T-cells, B-cells, macrophages).
Main Results:
- Early stage (1 week): Corneal edema and infiltration of polymorphonuclear leukocytes and helper/inducer T-cells (Th/i).
- Middle stage (2 weeks): Geographic corneal ulceration with persistent polymorphonuclear leukocytes and increasing Th/i cells, alongside the emergence of B-cells.
- Late stage (3 weeks): Dense stromal scarring with a shift to a predominant B-cell population and decreased overall inflammatory cells. Mild uveal inflammation with increased Ia staining in the choroid was observed throughout.
Conclusions:
- The immune response in HSV-1 keratouveitis evolves over time, characterized by an initial polymorphonuclear leukocyte and T-cell infiltrate followed by a significant B-cell presence in later stages.
- These findings highlight the dynamic nature of immune cell involvement in viral keratitis and suggest B-cells play a role in the late-stage pathology, potentially contributing to scarring.
- The murine model effectively recapitulates key inflammatory features of human HSK, providing a valuable platform for further research into therapeutic interventions.