Background: Auto-immune responses to Collagen type V (ColV) have been associated with coronary artery disease and lung or heart transplant rejection in humans and murine models. Unlike the Th1 response to EBV or tetanus toxoid, the Th17 mediated ColV response in these patients was also dependent on IL-1β, TNFα, IL-22 and a functional P2X7R. We have recently reported the presence of Th17 dependent cellular immune responses to ColV, kα-1tubulin and Vimentin, three transplant associated self-antigens, in healthy individuals by removing CD39⁺ Tregs or by neutralizing Treg cytokines (TGFβ). In addition, we observed that Th17 cells from ColV reactive patients had significantly higher expression of P2X7R than Th1 cells. With these data in mind, targeting the polymorphic P2X7R to inhibit Th17 vs Th1 cellular immune responses in transplant patients is a promising strategy to prevent chronic organ rejection. Clinical trials using P2X7R antagonists to block Th17-pathologies have largely been unsuccessful due in part to the failure to control for the genetic predisposition in humans to have normal/high (60-70%) or low (40-30%) P2X7R pore function. In preparation for NHP transplant studies, we tested the hypothesis that ColV, kα-1tubulin and Vimentin responses were present in healthy Rhesus Macaques after Treg removal/functional inhibition, and that these responses were P2X7R dependent. Results: Using intra-cellular cytokine staining, we found that removal of CD25⁺ T cells from PBMCs of healthy NHPs uncovers a population of CD4 T cells that produce IL17, TNFα and GM-CSF in a P2X7R dependent manner in response to overnight stimulation with ColV, kα-1tubulin and Vimentin but not to Collagen-I. This pre-existing, Th17 memory response in NHPs parallels the footpad swelling response in the 24 hour tvDTH assay. In addition, we found a similar frequency of normal/high vs low P2X7R pore function animals amongst the NHP group as that reported in humans. Conclusions: Consistent with our hypothesis, ColV, kα-1tubulin and Vimentin responses were detected after CD25⁺ T cell removal in NHPs and this response was dependent on IL-17, TNFα and P2X7R activity. The Rhesus Macaque is therefore the ideal animal model for investigating P2X7R immuno-therapies designed at inhibiting Th17 mediated chronic rejection of organ grafts with little impact on Th1 mediated responses such as those to viral, bacterial or fungal pathogens.

CITATION INFORMATION: Sullivan J, Jankowska-Gan E, Kaufman D, Denlinger L, Burlingham W. Non-Human Primate Auto-Immune Responses to Col V, Kα-1Tubulin and Vimentin Are P2X7R Dependent. Am J Transplant. 2017;17 (suppl 3).

« Back to 2017 American Transplant Congress