Comparison of topical interleukin-1 vs tumor necrosis factor-alpha blockade with corticosteroid therapy on murine corneal inflammation, neovascularization, and transplant survival (an American Ophthalmological Society thesis)

Abstract

Purpose: Interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) play critical roles in mediating corneal inflammation. In this study, topical blockade of IL-1 and TNF-alpha, alone or in combination, was compared to conventional corticosteroid anti-inflammatory therapy in suppressing infiltration of the cornea by antigen-presenting Langerhans cells (LCs) and in promoting corneal transplant survival in a mouse model of keratoplasty.

Methods: Study drugs included topical 2% IL-1 receptor antagonist (IL-1Ra), 1.5% soluble TNF-alpha receptor (sTNFR), and 1% prednisolone phosphate (Pred), all formulated in hyaluronic acid vehicle. Fifty eyes of BALB/c mice were used for LC studies where the numbers of LCs were determined 1 week after electrocautery to the corneal surface or transplantation of C57BL/6 corneas. Additionally, 65 BALB/c mice received corneal allografts and were randomized to receive one of the following for 8 weeks: (1) IL-1Ra, (2) sTNFR, (3) Pred, (4) combined IL-1Ra and Pred, or (5) vehicle alone.

Results: Mean suppression of LC infiltration after electrocautery or transplantation was 67% and 71%, respectively, for IL-1Ra, 40% and 62% for sTNFR, 70% and 72% for sTNFR+IL-1Ra, and 77% and 78% for Pred alone. Rejection rates were 15% for IL-1Ra (P = .01), 38% for sTNFR (P = .1), 17% for Pred (P = .02), and 7% for combined IL-1Ra+Pred (P = .002) as compared to 69% for the vehicle-treated group. IL-1Ra and Pred, but not sTNFR, significantly inhibited post-transplantation neovascularization.

Conclusions: Topical IL-1Ra and prednisolone are comparable in their capacity to promote graft survival. sTNFR therapy, though effective, has much lower efficacy as compared to IL-1Ra or Pred. Combination IL-1Ra and steroid therapy offers only minimal added efficacy over either agent used alone.

FIGURE 1

Number of major histocompatibility complex class II+ Langerhans cells (LCs) in the cornea 1 week following cauterization, based on treatment modality. Topical application of IL-1Ra (P = .01), sTNFR (P = .04), sTNFR + IL-1Ra (P = .01), and Pred (P = .001) leads to significant reduction in number of infiltrating LCs as compared to vehicle-treated controls. Topical Pred alone leads to a suppression level significantly greater than that observed for sTNFR (P = .03) but not compared to IL-1Ra (P = .4). Bars represent standard error of the mean.

FIGURE 2

Number of limbic host–derived major histocompatibility complex class II+ Langerhans cells (LCs) in the grafted cornea 1 week after transplantation, based on treatment modality. Topical application of IL-1Ra (P = .01), sTNFR (P = .02), sTNFR + IL-1Ra (P = .01), and Pred (P = .01) leads to significant reduction in number of infiltrating LCs as compared to vehicle treatment alone. Bars represent standard error of the mean.

FIGURE 3

Mean percent decrease in Langerhans cell (LC) recruitment to cornea in two models of corneal inflammation (cauterization and transplantation) based on treatment modality. In the aggregate, IL-1Ra and steroid therapy have comparable efficacy, which is greater than that observed for sTNFR.

FIGURE 4

Mean corneal transplant opacity scores among 5 different treatment groups at 1 and 4 weeks postkeratoplasty. At 1 week, maximal suppression in graft opacity is observed with combined IL-1Ra and Pred therapy. By 4 weeks, all treatment regimens demonstrate significantly lower opacity scores as compared to the vehicle-treated group. Bars represent standard error of the mean.

FIGURE 5

Rejection rates at 4 and 8 weeks of follow-up for corneal allografts, based on treatment regimen. By completion of the 8-week follow-up period, maximal (nearly 90%) reduction in rejection is seen with combined IL-1Ra and Pred therapy (7%) as compared to administration of vehicle alone (69%).

FIGURE 6

Opacity scores for all grafts over 8-week follow-up period: Top left, Vehicle treatment (N = 13); Top middle, sTNFR treatment (N = 13); Top right, IL-1Ra treatment (N = 13); Bottom left, Pred treatment (N = 12); and Bottom right, Pred and IL-1Ra (N = 14

FIGURE 7

Kaplan-Meier survival curves for all treatment regimens as compared to vehicle treatment alone. Treatment with IL-1Ra (P = .01), combined IL-1ra and Pred (P = .002), and Pred (P = .02) demonstrate higher efficacy in suppressing graft rejection as compared to sTNFR (P = .1) treatment.

FIGURE 8

Mean scores for posttransplantation neovascularization (NV) at weeks 1, 4, and 8 based on treatment regimen. Overall, maximal angiostatic effect is seen with Pred alone and combined IL-1Ra and Pred therapy. Bars represent standard error of the mean.

FIGURE 9

Percent of corneal transplants with neovascularization (NV) score >2 at 1, 4, and 8 weeks postgrafting based on treatment regimen. Overall, although in the early postoperative period all treatments show angiostatic efficacy, by 8 weeks maximal suppression of NV as compared to the vehicle-treated eyes is seen with IL-1Ra and/or Pred therapy.

FIGURE 10

Percent reduction in posttransplantation neovascularization (NV) over 8 weeks based on treatment regimen. IL-1Ra alone (38%), Pred alone (63%), and combined IL-1Ra and Pred (59%) demonstrate higher efficacy in NV suppression, whereas the suppressive effect (16%) of sTNFR is very modest.

FIGURE 11

Neovascularization (NV) scores for all grafts over 8-week follow-up period, based on treatment regimen and rejection status: Top left, Vehicle treatment (N = 13); Top middle, sTNFR treatment (N = 13); Top right, IL-1Ra treatment (N = 13); Bottom left, Pred treatment (N = 12); and Bottom right, Pred and IL-1Ra (N = 14).