Abstract
Purpose: :
To investigate IL-17 expression in conjunctival tissue specimens obtained from patients with active chronic allergic eye disease (CAED), mucous membrane pemphigoid (MMP), seasonal allergic conjunctivitis (SAC) and non-inflamed controls, and in tear fluids.
Methods: :
Two-colour immunostaining of glycolmethacrylate-embedded, tarsal (CAED; n=6) or bulbar (MMP, n=6; SAC, n=7; controls, n=6) conjunctival tissue sections was performed using anti-human CD4 mAb and anti-IL-17A mAb. Sections were graded for staining intensity in epithelium and stroma. Levels of IL-17A, gamma interferon (IFNγ), interleukin (IL)-5 and tumor necrosis factor alpha (TNF) were simultaneously assayed in cell-free tear fluid specimens from CAED (n=35) and controls (n=15) using multiplex bead arrays with flow cytometry.
Results: :
Epithelial and stromal staining for IL-17 was observed in both CAED (P<0.01) and MMP (P<0.05) but not in SAC or controls. Significant increases in CD4+IL-17+ (Th17) cells were observed in CAED but not in MMP. Some IL-17+dendritic-like cells were also seen in the stroma in MMP and control conjunctival tissues. IL-17A levels were below the level of detection in all CAED tear specimens, whereas TNF was detected in 34 of 35 CAED tear fluids (mean 110.0+/-18.5 pg/ml) and 10 of 15 controls (54.9+/- 21.8 pg/ml). IL-5 was detected in 18 of 25 CAED tear fluids (82.6+/-27.1 pg/ml) and IFNγ detected in only 5 of 35 CAED tear specimens.
Conclusions: :
Th17 cells were significantly increased in chronic allergic eye disease but not in MMP whilst intense IL-17 staining of the epithelium was observed in severe forms of chronic allergic and autoimmune conjunctivitis, suggesting a role for Th17 and/or epithelial cells in these chronic conjunctival diseases.
Keywords: conjunctivitis • inflammation • immunohistochemistry