Characterization of T-lymphocytes in the anterior uvea of eyes with chronic equine recurrent uveitis.
Abstract: Equine recurrent uveitis (ERU), a chronic, recurrent inflammation primarily of the anterior uveal tract, is the most common cause of blindness in horses. Recently, T-lymphocytes have been found to be the most numerous cell type to infiltrate the anterior uveal of horses with ERU. In the present study, we characterized the T-lymphocyte population in the anterior uveal tract of eyes of horses with chronic ERU by evaluating the microscopic appearance (histopathologic features), the T-lymphocyte subsets, and the relative levels and amounts of T-lymphocyte cytokine mRNA in the anterior uvea. Seven inflamed eyes (from six horses with chronic ERU) and 5 normal eyes (from five horses with nonocular problems) were studied. After clinical examination, the eyes were removed, ocular fluids were aspirated, and anterior uveal tissues (iris and ciliary body) were processed for histologic and molecular (RNA isolation) analyses. Histologic examination by hematoxylin and eosin (H and E) staining and immunohistochemistry evaluating T-lymphocyte subsets (anti-CD4, CD8, CD5) were performed for each sample. RNA samples were analyzed for levels of messenger (m) RNA specific for interleukin (IL)-2, 4, and interferon-gamma (IFNgamma) by quantitative reverse transcriptase polymerase chain reaction (QRT-PCR). Eyes with ERU exhibited characteristic clinical signs, including corneal edema, aqueous flare, posterior synechia, corpora nigra degeneration, and cataract formation. Histologically, infiltration of the uveal tract with lymphocytes, plasma cells, and macrophages was most evident in the ciliary body and base of the iris. Loss of tissue structure (destruction) was most evident in the ciliary processes. Infiltrating lymphocytes were predominantly CD4+ T-cells (e.g. 48% CD4+ and 18% CD8+ in the ciliary body stroma), as determined by immunohistochemistry. Few inflammatory cells were observed in the normal eyes. The QRT-PCR results revealed increased transcription of IL-2 and IFNgamma and low IL-4 mRNA expression in eyes with chronic ERU compared to normal eyes, demonstrating a Thelper (Th) 1-like inflammatory response in eyes with ERU.
Publication Date: 1999-10-16 PubMed ID: 10522783DOI: 10.1016/s0165-2427(99)00082-3Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The study focuses on examining T-lymphocytes, a type of white blood cell, present in the anterior uvea of the eyes of horses suffering from equine recurrent uveitis (ERU), a common cause of blindness in horses.
Research Context
- Equine recurrent uveitis (ERU) is a chronic, recurring inflammation condition that primarily affects the anterior uveal tract of horses.
- The anterior uveal tract consists of the iris and the ciliary body.
- ERU is the most frequent cause of blindness in horses, and it has been recently discovered that T-lymphocytes are the most common cellular type infiltrating the anterior uveal tract in ERU instances.
Research Methodology
- In the study, the T-lymphocyte population in the anterior uvea of horses with chronic ERU was characterized.
- A total of seven inflamed eyes (from six horses with chronic ERU) and 5 normal eyes (from five horses with no ocular issues) were studied.
- Post clinical examination, the eyes were removed for further analysis.
- Anterior uveal tissues (iris and ciliary body) were processed for histologic and molecular (RNA isolation) analyses.
- Immunohistochemistry was used to assess T-lymphocyte subsets (anti-CD4, CD8, CD5) while quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) was used to analyze the levels of specific messenger (m) RNA (interleukin (IL)-2, 4, and interferon-gamma (IFNgamma)).
Findings
- ERU-affected eyes exhibited specific clinical signs such as corneal edema, aqueous flare, posterior synechia, corpora nigra degeneration, and cataract formation.
- There was notable infiltration of the anterior uvea (particularly the ciliary body and base of the iris) by lymphocytes, plasma cells, and macrophages.
- The ciliary process experienced maximum tissue structure loss due to this infiltration.
- Immunohistochemistry revealed that infiltrating lymphocytes were primarily CD4+ T-cells.
- Injection of lymphocytes, plasma cells, and macrophages was very rare in normal eyes.
- Using QRT-PCR, it was discovered that the transcription of IL-2 and IFNgamma were higher, while IL-4 mRNA expression was lower, in ERU-affected eyes as compared to normal eyes. This indicated a Thelper (Th) 1-like inflammatory response in ERU-affected eyes.
Cite This Article
APA
Gilger BC, Malok E, Cutter KV, Stewart T, Horohov DW, Allen JB.
(1999).
Characterization of T-lymphocytes in the anterior uvea of eyes with chronic equine recurrent uveitis.
Vet Immunol Immunopathol, 71(1), 17-28.
https://doi.org/10.1016/s0165-2427(99)00082-3 Publication
Researcher Affiliations
- Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA. brian_gilger@ncsu.edu
MeSH Terms
- Animals
- Chronic Disease
- Ciliary Body / immunology
- Ciliary Body / pathology
- Cytokines / biosynthesis
- Cytokines / genetics
- Horse Diseases / immunology
- Horse Diseases / pathology
- Horses
- Immunoenzyme Techniques / veterinary
- Iris / immunology
- Iris / pathology
- RNA, Messenger / metabolism
- Recurrence
- Reverse Transcriptase Polymerase Chain Reaction / veterinary
- T-Lymphocyte Subsets / immunology
- T-Lymphocytes / immunology
- Uveitis, Anterior / immunology
- Uveitis, Anterior / pathology
- Uveitis, Anterior / veterinary
Grant Funding
- EY11364 / NEI NIH HHS
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