Abstract
Purpose: :
Excessive fibrosis is a characteristic of ocular mucous membrane pemphigoid, also known as ocular cicatricial pemphigoid (OCP). Whilst the dysregulated fibrotic response may be a consequence of ongoing inflammation, it has also been proposed that fibroblasts from OCP patients are transformed into an abnormally active phenotype. The aim of this study was to investigate whether there are any phenotypic differences in functional fibroblast activity between conjunctival fibroblasts from OCP patients compared with healthy controls.
Methods: :
Bulbar conjunctival biopsies from OCP patients were taken both during active disease (n=11) and following immunosuppressive treatment (n=8). Biopsies from age-matched patients with healthy conjunctiva served as controls (n=11). Conjunctival fibroblasts were cultured for 24h in serum-free conditions before assaying for cell division using CFSE staining. Supernatants were collected from fibroblast-populated relaxed collagen lattices and evaluated by ELISA for collagen I secretion and by multiplex antibody array to simultaneously detect 7 matrix metalloproteinases (MMPs) and 3 tissue inhibitor of matrix metalloproteinases (TIMPs).
Results: :
Pemphigoid conjunctival fibroblasts had increased numbers of dividing cells compared with normal conjunctival fibroblasts (7026 ± 2020 vs 1216 ± 558 divided cells per 5000 events, P=0.01). They secreted increased levels of collagen I (66 ± 6ng/ml vs 31± 3ng/ml, P=0.03) and MMP-3 (p=0.006), and produced decreased levels of MMP-13 (P=0.02) compared with controls.
Conclusions: :
Conjunctival fibroblasts from patients with OCP appear to have a fibrotic phenotype which is maintained in vitro. This has important implications for anti-fibrosis therapy. Developing effective antifibrotic therapies will require understanding of the mechanisms that both induce and maintain the profibrotic phenotype.
Keywords: wound healing • conjunctiva • autoimmune disease