Abstract
Purpose: :
Inflammation and apoptosis participate to dry eye pathogenesis. Little is known about the different expression of mediators in different forms of dry eye. Aim of this paper is to study the expression, in two different forms of dry eye, of metalloproteinase (MMP)9, a marker of inflammation, and tranglutaminase (TG)2, one of the few genes induced during apoptosis, before and after treatment with loteprednol etabonate (LE).
Methods: :
The expression of MMP9 and TG2 was examined in conjunctival epithelium specimens obtained by conjunctival imprinting from 10 Sjögren’s syndrome (SS) patients (9 F, mean age±SD 61.6 ± 13.6); 10 meibomian gland dysfunction (MGD) patients (7 F, age 55.2±10); and 5 normal subjects (CTRL) (5 F, age 45.2±15.7). All subjects underwent to the following tests: Symptom questionnaire (0-3 score), break up time (BUT), fluorescein corneal stain, lissamin green conjunctival stain, Schirmer’s I test, conjunctival imprints from the supero-nasal, superior and supero-temporal sites of the bulbar conjunctiva were obtained to be processed for real time RT-PCR and for immunostaining for MMP9 and TG2. Patients underwent to a 15 days treatment with 1 drop t.i.d. of LE. Tests were repeated after the treatment period.
Results: :
The symptom score was lower in CTRL (p<0.001 vs SS and MGD). BUT was lower in SS (p=0.01 vs SS and p<0.001 vs CTRL) and in MGD (p<0.001 vs CTRL) Fluorescein corneal score was higher in SS and MGD (p<0.001 vs CTRL). Lissamin green score was higher in SS (p=0.003 vs CTRL). Schirmer’s I test was lower in SS (p<0.001 vs MGD and CTRL). The semiquantitative data obtained by real time PCR, normalized to the internal control GAPDH showed that MMP9 expression was higher in SS (22.5±7.6, p<0.001 vs MGD and CTRL); and in MGD (12±3.7, p=0.0009 vs CTRL) than in CTRL (1±0.02). The expression of TG2 was higher in SS (33.7±15.7, p<0.001 vs MGD and CTRL), and in MGD (7.7±6, p<0.05 vs CTRL) than in CTRL (2±0.02). The treatment with LE was able to reduce all the clinical parameters and the expression of the studied inflammatory marker.
Conclusions: :
The expression of MMP9, marker of inflammation, and TG2, enzyme induced with apoptosis, is significantly higher in SS than in patients with a different type of dry eye such as MGD. The treatment with LE reduced the signs and markers of inflammation in dry eye patients.
Keywords: conjunctiva • immunohistochemistry • gene/expression