The prior exposure of CD4+ T cells to alloantigen blunts their secretion of the reparative growth factor amphiregulin

Abstract Objective Chronic rejection (CR) manifests after transplantation as function-limiting allograft fibrosis and vasculopathy. Insights into the mechanisms leading to CR are needed to develop effective therapies. The aggressive development of fibrosis during CR is similar to that observed in unproductive injury repair. Thus, we investigated how alloantigen (AlloAg) shapes novel mechanisms of immune-mediated tissue repair. Amphiregulin (Areg) is a growth factor secreted by innate and adaptive immune cells in response to IL-33 released during tissue injury. As IL-33 and Areg are implicated in muscle, epithelium, and nerve repair, we defined how AlloAg recognition by CD4+ T cells modulates IL-33-induced Areg secretion. Method C57BL/6 mice transgenic for a TCR recognizing a BALB/c-derived alloAg (Eα52–68) presented on I-Ab were administered IL-33 or Eα52–68 alone, or combined, 10 days before CD4+ T cell isolation. Areg secretion by isolated CD4+ during 4 days of culture with IL-33 or Eα52–68 was measured by ELISA. The signaling mediating Areg secretion was defined using inhibitors. Results CD4+ T cell exposure to IL-33 prior to alloAg secreted Areg upon de novo AlloAg exposure or secondary IL-33 stimulation. Exposure to AlloAg before IL-33, however, limited the capacity of alloreactive T cells to secrete Areg in response to either IL-33 or alloAg. Using the P38 inhibitor SB203580 and NF-κB inhibitors MG132 and TCPA-1 we established that both NF-κB and p38 are critical CD4+ T secretion of Areg. Conclusion Our studies suggest that recognition of AlloAg disrupts a reparative response mediated by CD4+ T cells. Limiting the reparative capacity of non-self T cells may aid pathogen clearance, but support development of CR in after transplant.