Trabeculotomy in a Behçet's Disease Patient One Week after Infliximab Administration

A Pilot Study on Ocular Safety and Efficacy of Infliximab as an Antifibrotic Agent After Experimental Glaucoma Filtration Surgery

Introduction

Tumor necrosis factor-α (TNF-α) is a multifunctional, proinflammatory cytokine that mediates pleiotropic biological functions, especially inflammation and immunoregulation. We hypothesized that blocking TNF-α with a monoclonal antibody would decrease inflammation and subconjunctival scarring in an animal model of experimental filtration surgery.

Methods

In a randomized, prospective, masked-observer study, 30 New Zealand albino rabbits underwent glaucoma filtration surgery. The animals were allocated to receive either intraoperative application of infliximab (group A) or mitomycin C (MMC) at a concentration of 0.2 mg/ml (group B) or balanced salt solution (BSS, control) (group C). Different infliximab doses, namely 1.0, 2.0, 3.0, 4.0, 5.0 mg in 0.1 ml, were applied. Bleb survival and characteristics were evaluated over a 30-day period. The animals were killed on postoperative day 15 or 30. Histology of the operated eyes was performed to evaluate and grade the amount of scarring in each group. Cellular density was evaluated in each case.

Results

Infliximab did not appear to improve outcomes in this model of glaucoma filtration surgery. Bleb survival was significantly higher in the MMC group compared to the other groups (p < 0.001 for both comparisons). Vascularity was also significantly lower in the MMC group compared to the other groups (p = 0.018 for both comparisons). There was a significant decrease in cellular density in the MMC group compared to the control (p = 0.0352) and the infliximab group (p < 001).

Conclusion

Our results have shown that trabeculectomies in the infliximab group failed faster and displayed more scarring, compared to the control and MMC groups. This outcome suggests that the infliximab doses used in this pilot study resulted in a subconjunctival TNF-α concentration, which acted as a stimulator to fibroblasts.

Infliximab counteracts tumor necrosis factor-α-enhanced induction of matrix metalloproteinases that degrade claudin and occludin in non-pigmented ciliary epithelium

Infliximab, a monoclonal antibody directed against human tumor necrosis factor-alpha (TNF-α), effectively treats anterior uveitis, which can accompany Behçet's disease. Here, we investigated the underlying mechanism of this action. We examined human, non-pigmented ciliary epithelial cells (HNPCECs), which make up the blood-aqueous barrier (BAB) in the uvea. We measured the expression levels of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs in the presence or absence of TNF-α using quantitative, real-time polymerase chain reaction and enzyme-linked immunosorbent assays. The expression of MMP-1, MMP-3, and MMP-9 increased in the presence of TNF-α, and the addition of infliximab reversed the increase. The TNF-α effects were more attenuated when infliximab was added before than when it was added after TNF-α exposure. Gelatin zymography demonstrated that the protease activity of these MMPs was also increased in the presence of TNF-α and attenuated with infliximab. Immunostaining showed that MMP-1, MMP-3, and MMP-9 degraded claudin-1 and occludin in HNPCECs and in non-pigmented ciliary epithelial cells of the swine ciliary body. In a monolayer of HNPCECs, we found that permeability was significantly increased with MMP treatment. Thus, TNF-α increased levels of MMPs in cells that form the BAB, and MMPs degraded components of the tight junctions in the BAB, which increased permeability through the cellular barrier. Furthermore, infliximab effectively attenuated the TNF-α-induced increases in MMP expression in cells that make up the BAB. These findings might suggest a basis for the clinical prevention of anterior uveitis.