Correlation between Tissue Characterization and Dynamic Expression of Matrix Metalloproteinase-2 and Its Tissue Inhibitor in Conjunctival Filtering Bleb of Rats

Abstract

Purpose Using rat conjunctival bleb model, we correlated changes morphology and histology in the bleb with changes in MMP-2 and TIMP-2 levels. Methods Filtering surgeries were performed on rats. Dynamic changes in morphology and histopathology were observed using HE staining. Expression of MMP-2 and TIMP-2 was determined by immunofluorescence microscopy and western blotting. Results Well-elevated filtering blebs formed and persisted for an average of 12 days. Histological examination showed that inflammatory was dominant in postoperative days 1–3, and proliferating manifestation became the main sign 5 days later. Western blot showed that MMP-2 was downregulated 1 day after surgery, upregulated at 3 days, and observed with a peak at 7 days; then it persisted until 28 days. The difference was statistically significant (F = 280.18, p < 0.01).TIMP-2 was upregulated 1 day after surgery and observed with a peak at 5 days; then it persisted until 28 days. The difference was statistically significant (F = 145.34, p < 0.01). Conclusions During the processes of conjunctival filtering bleb and scar formation in rats, the changes in MMP-2 and TIMP-2 levels in the filtering area, together with a corresponding proliferation of fibroblasts and the accumulation of collagen fibres, resulted in scarring of filtering blebs.

Exogenous Tissue Inhibitor of Metalloproteinase-2 Affects Matrix Metalloproteinase-2 Expression in Conjunctival Filtering Blebs and Bleb Scarring in Rats

“…Shima et al [ 10 ] detected expression of MMP-1 at the protein and mRNA levels by establishing a rabbit model of filtrating bleb scarring formation. Previous studies of conjunctival filtration bleb formation and scarring in rats suggested the dynamic expression of MMP-2 and TIMP-2 and the balance between these two proteins was closely related to the scarring of filtrating blebs [ 11 ]. Further studies on the specific inhibitory effect of TIMP-2 on MMP-2 may improve the success rate of filtration surgery by degrading the ECM of fibroblasts in Tenon's capsule and thus inhibiting filtration bleb scarring.…”

“…Our previous study showed that scar formation during wound repair was most critical within two weeks after surgery [ 11 ]. From days 1–3, HE staining revealed that the connective tissue of the bulbar conjunctiva was markedly oedematous and loose, with vascular dilation and containing an abundance of infiltrating neutrophils.…”

“…The remaining 114 rats were included in the experimental group and were randomly divided into three groups: normal saline group, empty plasmid group, and gene transfection group. Each rat in the experimental group was implanted with an anterior chamber drainage device in the right eye to successfully establish the conjunctival bleb model [ 11 , 12 ]: creating a limbus-based conjunctival flap, a full-thickness scleral tunnel was then created using a 29-gauge needle, which was inserted into the anterior chamber; a “bead” of fluid was visualized to confirm patency. The 10-0 nylon thread was used in suturing the conjunctiva and Tenon's capsule.…”

“…Our previous study examined the dynamic expression of MMP-2 and TIMP-2 during filtrating bleb formation and scarring in rat models of postoperative conjunctival filtration bleb scarring. We found that the balance between MMP-2 and TIMP-2 expression was closely related to filtration bleb scarring [ 11 ].…”

Influence of Intraocular Pressure Status on the Formation of Functional Filtering Blebs after Trabeculectomy on Rhesus Monkey eyes

“…For example, the induction of glaucoma animal models is highly recommended prior to glaucoma filtering surgeries (GFS) so as to more scientifically assess the effect and draw more convincing conclusions [3]. Currently, most studies used normal ocular tension animals to observe the postoperative scarring inhibition effect of new drugs and new equipment [4][5][6]. Different from the intraocular hypertension (OHT) model, the normal IOP animals may lead to potential biases in the research results.…”