Therapeutic regulation of systemic inflammation in xenograft recipients

Academic Article

Abstract

  • © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Inflammation is known to preclude tolerance after transplantation. We have previously shown that systemic inflammation in xenograft recipients (SIXR) precedes activation of coagulation in the absence of T cell responses. Accordingly, SIXR may amplify innate and adaptive immune responses against xenografts after pig-to-primate xenotransplantation, even with efficient immunosuppressive therapy. We evaluated the impact of anti-inflammatory agents on pro-inflammatory cytokines and chemokines in pig artery patch and heart xenograft recipients. Baboons received an artery patch (Group1, n=8) or heart (Group2, n=4) from genetically engineered pigs. All baboons received lymphodepletion with thymoglobulin (ATG) and costimulation blockade-based immunosuppression (anti-CD40 and/or CTLA4Ig). In Group1, baboons received either (i) no anti-inflammatory agents (n=2), (ii) cobra venom factor (CVF, n=2), (iii) α1-antitrypsin (AAT, n=2), or (iv) interleukin (IL)-6 receptor antagonist (IL-6RA, n=2). In Group2, all baboon received corticosteroids, either without (n=2) or with (n=2) IL-6RA. Serum IFN-γ, TNF-α, IL-1β, IL-17, IL-6, IL-8, MCP-1, and sCD40L levels were measured by Luminex. Fibrinogen, D-dimers, and C-reactive protein (C-RP) were also measured. Recipient baboon T cell proliferation was evaluated by mixed lymphocyte reaction (MLR) before and after transplantation. Pig and baboon tissue factor (TF) mRNA levels in heart xenografts were measured by RT-PCR. In no recipient was a marked increase in T cell response to pig cells observed after transplantation. In Groups 1 and 2, post-transplantation levels of IFN-γ, TNF-α, IL-1β, and IL-17 remained comparable to or lower than pre-transplant levels, except in one heart recipient that succumbed to CMV infection. In Group1, when no anti-inflammatory agent was administered, post-transplant levels of IL-6, IL-8, and MCP-1 were elevated. After CVF, IL-6, IL-8, and MCP-1 remained low. After IL-6RA, IL-6 and MCP-1 were elevated. After AAT, IL-8 was elevated. sCD40L became elevated intermittently in most recipients irrespective of the administered anti-inflammatory agent. In Group2, IL-6 was transiently elevated, particularly after IL-6RA administration. MCP-1 gradually increased by 2 months in Group2 recipients. sCD40L generally remained low except in one recipient. In Group1 and Group2 recipients, C-RP levels were elevated except after IL-6RA administration, while D-dimers were elevated regardless of administration of anti-inflammatory agent. In Group2, pig TF mRNA levels were increased in heart xenografts compared to naive pig hearts, irrespective of IL-6 receptor antagonist administration. Additionally, baboon TF mRNA levels were detectable in heart xenografts, but not in naive pig hearts. Some pro-inflammatory cytokines and chemokines are elevated in xenograft recipients, even with efficient T cell-directed immunosuppressive therapy. Persistent elevation of D-dimers, and individual cytokines and chemokines suggest a continuous inflammatory response, despite administration of anti-inflammatory agents. Systemic administration of combined anti-inflammatory agents as well as complement regulation may be essential to prevent SIXR after xenotransplantation.
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    Author List

  • Iwase H; Liu H; Li T; Zhang Z; Gao B; Hara H; Wijkstrom M; Long C; Saari R; Ayares D
  • Volume

  • 24
  • Issue

  • 2