Abstract
Purpose :
Cornea xenotransplantation is a promising procedure to minimize the gap between a limited availability and an increasing demand for corneas to treat blindness. Compatibility of the transplanted cornea to the recipient host immune system is a crucial factor for graft acceptance. Data from non-human primates propose that rejection of xenotransplanted cornea is mediated by the innate immune system via activation of the complement system. Here, we assessed the dependence of complement and the TLR co-receptor CD14 on porcine cornea-induced acute inflammatory response in human whole blood ex vivo.
Methods :
Human whole blood, anticoagulated with the thrombin inhibitor lepirudin, was incubated at 37°C with three groups of differently treated corneas: A: native porcine cornea (NPC); B: decellularized porcine cornea (DPC); C: gamma irradiated decellularized porcine cornea (g-DPC). The incubations were carried out with and without complement C5 and/or CD14 inhibitory antibodies, eculizumab and r18D11 respectively. Complement activation was evaluated after incubation for one hour and cytokine levels after four hours. Complement activation was assessed by measuring soluble C4bc and C3bc fragments, and the soluble terminal C5b-9 complement complex (sC5b-9) using ELISA. Cytokines were measured using a multiplex based 27-plex assay.
Results :
All the corneas activated complement and induced cytokine release. As expected, the C5-inhibitor, but not the CD14 inhibitor blocked formation of sC5b-9, whereas as none of the antibodies affected C4 and C3 activation. Pro-inflammatory cytokines including IL-1β, IL-6, IL-8, MIP-1α and MIP-1β were elevated in response to all three cornea groups. The elevated release of IL-1β, and IL-6 were generally higher by DPC compared to NPC and g-DPC, whereas the release pattern of IL-8, MIP-1α and MIP-1β were not affected by any of the cornea groups. The C5 and CD14 inhibitors, separately as well as in combination, inhibited the release of all above-mentioned cytokines induced by NPC. However, only IL-1β and IL-6 were reduced by CD14 inhibitor when induced by DPC and g-DPC.
Conclusions :
Porcine cornea activates the complement system and leads to increase release of pro-inflammatory cytokines when in contact with human whole blood. The cytokine response was inhibited using inhibitors of complement component C5 and the TLR molecule CD14.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.