Novel Insight into the Inflammatory and Cellular Responses Following Experimental Glaucoma Surgery: A Roadmap for Inhibiting Fibrosis

Abstract

Failure after glaucoma filtration surgery is attributed to fibrosis at the operated site. To understand the wound healing process after glaucoma filtration surgery, we have developed a mouse model for glaucoma filtration surgery which closely mimics the clinical response. In this study, we describe a systematic analysis of the wound healing response in vivo. Our data revealed that the post-surgical tissue response was separable into two distinguishable phases. The early "acute inflammatory" phase was characterized by significantly increased transcript expression of Vegfa, Cxcl1, Cxcl5, Ccl2, Ccl3, Ccl4, Gmcsf and specific Mmps as well as greater infiltration of monocytes/macrophages and T cells. The late "fibrotic" phase was characterized by an increased expression of Tgfb2 and extracellular matrix genes as well as a notable reduction of infiltrating inflammatory cells. Significantly, more mitotic cells were observed at both time points post-surgery. Subconjunctival fibroblasts may be involved in both phases since they have the capacity to reiterate the in vivo gene expression profiles upon either pro-inflammatory or pro-fibrotic cytokine stimulation. Given that the cellular and molecular targets that govern the early and late phases of wound healing are distinct and time sensitive, a multi-targeted therapeutic approach to sequentially inhibit inflammation and fibrogenesis at the critical time point may lead to improved surgical outcomes in glaucoma filtration surgery.

Upregulation of distinct collagen transcripts in post-surgery scar tissue: a study of conjunctival fibrosis

“…The development of a mouse model of GFS (Seet et al, 2010) enables a quantitative assessment of fibrotic development through molecular analyses (Seet et al, 2013). This mouse model responded to mitomycin C (MMC), a commonly applied adjunctive antifibrotic therapy in clinical GFS, in a similar manner to that observed in patients (Seet et al, 2011).…”

“…This mouse model responded to mitomycin C (MMC), a commonly applied adjunctive antifibrotic therapy in clinical GFS, in a similar manner to that observed in patients (Seet et al, 2011). The fibrotic phase in this mouse model, which is measurable on day 7 post-experimental surgery, is marked by increased expression of extracellular matrix genes, including type I collagen ( Col1a1 ) (Seet et al, 2013). Col1a1 expression, as a quantitative marker for conjunctival fibrosis, can be measured at both the mRNA and protein levels via real-time quantitative polymerase chain reaction (qPCR) and immunoblotting techniques in the mouse model.…”

“…Col1a1 expression, as a quantitative marker for conjunctival fibrosis, can be measured at both the mRNA and protein levels via real-time quantitative polymerase chain reaction (qPCR) and immunoblotting techniques in the mouse model. Both techniques are independently quantitative and have the capacity to assess the entire scarring area (Seet et al, 2013). …”

Angiogenesis in glaucoma filtration surgery and neovascular glaucoma: A review

“…Seet et al 99 developed a systematic spatio-temporal analysis of the phases in the wound healing response to glaucoma filtration surgery using a mouse model. They observed that this post-surgical tissue response can be separated into two distinctive phases.…”

“…119 Among different VEGF isotopes, VEGF-A is the only one showing significantly decreased expression in later stages of wound healing. 99 This suggests that VEGF-A may be involved in the transition from the early to late phases of wound healing. Among the different isoforms of VEGF-A, VEGF-121, VEGF-165, and VEGF-189 are expressed in rabbit Tenon fibroblasts.…”