Alloantibody and Complement Promote T Cell-Mediated Cardiac Allograft Vasculopathy through Non-Canonical NF-κB Signaling in Endothelial Cells
Background—Cardiac allograft vasculopathy (CAV) is the major cause of late allograft loss following heart transplantation. CAV lesions contain alloreactive T cells that secrete IFN-γ, a vasculopathic cytokine, and occur more frequently in patients with donor specific antibody (DSA). Pathologic interactions between these immune effectors, representing cellular and humoral immunity, respectively, remain largely unexplored.
Methods and Results—We used human panel reactive antibody (PRA) to form membrane attack complexes (MAC) on allogeneic endothelial cells in vitro and in vivo. Rather than inducing cytolysis, MAC upregulated inflammatory genes, enhancing the capacity of EC to recruit and activate allogeneic IFN-γ-producing CD4+ T cells in a manner dependent upon activation of non-canonical NF-κB signaling. Non-canonical NF-κB signaling was detected in situ within EC both in renal biopsies from transplant patients with chronic antibody-mediated rejection and in PRA-treated human coronary artery xenografts in immunodeficient mice. Upon re-transplantation into immunodeficient hosts engrafted with human T cells, PRA-treated grafts recruited more IFN-γ-producing T cells and enhanced CAV lesion formation.
Conclusions—Alloantibody and complement deposition on graft EC activate non-canonical NF-κB signaling, initiating a pro-inflammatory gene program that enhances alloreactive T cell activation and development of CAV. Non-canonical NF-κB signaling in EC, observed in human allograft specimens and implicated in lesion pathogenesis, may represent a target for new pharmacotherapies to halt the progression of CAV.
- Received April 2, 2013.
- Revision received September 3, 2013.
- Accepted September 4, 2013.