Abstract
Purpose:
It has recently been demonstrated that CCR7-expressing dendritic cells contribute to the immunopathogenesis of allergic conjunctivitis in the mouse model. However, whether CCR7 plays a similar role in the human condition is unknown. The aim of this study was to investigate conjunctival expression of CCR7 following allergen challenge in seasonal allergic conjunctivitis (SAC) patients.
Methods:
Human anonymised conjunctival tissue biopsies (3 micron) were obtained from SAC donors (n=7, from all males; age: 18-65 years) at 8 hr post allergen challenge. Control, non-inflamed, conjunctival tissues collected from anonymised human donors (n=5 from 3 males; age: 31-57) were also examined. Donor tissues were collected after obtaining informed consent and Local Research Ethics approval in accordance with the Declaration of Helsinki. Tissue sections were stained for anti-human CCR7 (eBioscience), anti-human neutrophil elastase (DAKO), or isotype-matched control rat IgG2a kappa antibody (eBioscience and visualized with a DAB staining kit (Vectastain). Two independent, masked observers enumerated positively stained cells per biopsy area (at least three fields).
Results:
CCR7-expressing cells were detected mainly within the subepithelium and stromal areas. Over 70% of tissues from SAC patients stained positive for CCR7, compared to only 20% from control patients. The numbers of CCR7-expressing cells did not appear to correlate with neutrophil numbers, as the difference in the number of neutrophils between control (mean: 44.0 ± 14.0 cells per biopsy) and SAC (mean 82.9 ± 117.8 cells per biopsy) patients was not statistically significant.
Conclusions:
CCR7-expressing cells are detectable in human conjunctival tissues and appear to be upregulated during acute inflammation in SAC.
Keywords: 475 conjunctivitis •
490 cytokines/chemokines •
474 conjunctiva