Influence of interleukin-1alpha and tumor necrosis factor-alpha production on corneal graft survival

Abstract

Aim: To determine pro-inflammatory cytokine secretion from human corneas with different pathology and to establish whether cytokine profile influences corneal graft outcome.

Method: Secretion of both proinflammatory cytokine interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha was measured after cultivation of 47 corneas collected from corneal graft recipients suffering from different corneal diseases. Non-inflammatory corneal diseases were keratoconus (n=8), keratoglobus (n=2), bullous keratopathy (n=11), and Groenouw stromal dystrophy type II (n=2), whereas inflammatory included vascularized corneal scar (n=14), rejected graft (n=6), and corneal ulcer (n=4). Corneas were cultivated at 37 degrees C for 24 hours and frozen until cytokine detection was measured by immunoassay. Donor corneas unsuitable for transplantation were used as controls (n=7). Corneal graft recipients were followed at least 18 months and rejection rate was calculated for each group.

Results: The median concentration of IL-1alpha secreted from corneas of recipients with non-inflammatory diseases was 2.47 pg/mm(3) (range, 0.13-9.95). In inflammatory corneal diseases, IL-1alpha concentration was significantly higher (median, 5.92 pg/mm(3); range, 0.48-12.68; P=0.005). IL-1alpha production in controls (median, 0.63 pg/mm3; range, 0.36-1.29 pg/mm(3)) was significantly lower than in inflammatory corneal diseases (P<0.001) and non-inflammatory diseases (P=0.008). Low level of TNF-alpha was detected only in 5 cases of vascularized corneal scars, 3 cases of bullous keratopathy, and 3 cases of graft rejection. Rejection rate was significantly higher in inflammatory than in non-inflammatory group (46% vs <10%, respectively, P=0.008). IL-1alpha and TNF-alpha were absent from all patient's sera, confirming its local intra-ocular production.

Conclusion: Increased production of IL-1alpha in corneal recipients with inflammatory diseases suggests its role in corneal graft rejection in humans.

Figure 1

Interleukin (IL)-1α production in diseased human corneas and controls. Human corneas with inflammatory and non-inflammatory diseases were harvested during corneal transplantation, while control corneas were obtained from the eye bank, and cultivated for 24 hours. Concentration of IL-α in corneal supernatant was measured by ELISA, and expressed as median (closed square) with lower and upper quartiles (open square) and minimum and maximum (T lines). The median concentration of IL-1α in inflammatory corneal diseases was significantly increased compared with non-inflammatory ones (P = 0.005) and controls (P<0.001, post hoc Man-Whitney test). Kruskal-Wallis ANOVA and Ranks test the confirmed differences between the tested groups (P = 0.001).

Figure 2

Kaplan-Meier curves showed that time period to graft rejection was shorter and graft rejection was higher in inflammatory group of patients (P = 0.004). Circle – rejected corneas; plus sign – non-rejected corneas; full line – corneas with inflammatory diseases; dotted line – corneas with non-inflammatory diseases.