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J. Dunmire, S. Al-Shahwan, I. Al-Jadaan, R. Bouhenni, J. D. Lam, P. R. Edward, D. P. Edward; Immunohistochemical Analysis of β-Defensin 1 & 2 in Leaking Blebs Following Trabeculectomy. Invest. Ophthalmol. Vis. Sci. 2010;51(13):624.
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© ARVO (1962-2015); The Authors (2016-present)
Defensins, a family of small antimicrobial peptides, are secreted by ocular surface epithelium as part of the innate immunity. Human β-Defensin 1 (HBD1) is constitutively expressed in the conjunctiva while Human β-Defensin 2 (HBD2) is upregulated in response to infection. Mitomycin C trabeculectomy (MMT) predisposes patients to bleb complications. We hypothesized that with bleb leaks, a risk factor for blebitis, defensin regulation is altered in the conjunctival epithelium. To test this hypothesis, HBD1 and HBD2 expression was examined by immunohistochemistry in excised conjunctivae of patients with bleb leaks after MMT.
Clinical data, including history of bleb leakage, previous blebitis, and type of glaucoma, was recorded. HBD1 and HBD2 expression was studied using an indirect immunoperoxidase technique on conjunctival sections from normal human control (n=15) and excised leaking blebs following MMT (n=13). Labeling was analyzed in normal conjunctival epithelium and in leaking blebs at both the bleb dome and specimen periphery. Staining intensity was quantified using Image Pro 6.3 and was expressed as fold difference relative to normal. Statistical differences were analyzed by ANOVA. Clinical and staining data were subjected to Pearson’s correlation analysis.
Normal conjunctiva showed diffuse HBD1 and HBD2 cytoplasmic immunoreactivity (IR) in the epithelium. Both HBD1 and HBD2 IR were significantly increased in bleb domes with epithelial thinning. Staining intensity in thinned epithelium of blebs was 9.78+/-3.37 fold (p<=0.01) and 5.14+/-1.65 fold (p<=0.05) greater than normal control for HBD1 and HBD2 respectively. No significant difference was observed for HBD1 and HBD2 IR in bleb periphery compared with normal control. However, HBD2 IR in bleb periphery was 8.56+/-2.74 fold less than in thinned bleb epithelium (p<=0.05). The degree of HBD1 and HBD2 IR showed no correlation with the demographics or other clinical factors recorded.
Increased IR of HBD1 and HBD2 was demonstrated in areas of thinned epithelium in leaking conjunctival blebs whereas the bleb periphery was comparable to normal conjunctiva. The upregulation of these peptides may serve as a protective mechanism against infection in the presence of a leak or altered epithelial structure.
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