Immune Response to Tissue-Restricted Self-Antigens Induces Airway Inflammation and Fibrosis Following Murine Lung Transplantation

Immune responses against lung-associated self-antigens (self-Ags) are hypothesized to play a role in the development of chronic lung graft rejection. We determined whether immune responses to lung self-Ags, K-alpha-1-tubulin (K1T) and Collagen V (Col-V) in the absence of alloimmunity, could promote airway inflammation and fibrosis. Following syngeneic murine orthotopic lung transplantation (LTx) we administered antibodies (Abs) to either K1T or Col-V or in combination to both of these self-Ags. As compared to recipients of isotype control Abs, K1T Abs and/or Col-V Abs-treated recipients had marked lung graft cellular infiltration and bronchiolar fibrosis. This inflammation was also associated the accumulation of K1T and Col-V-specific interferon-+ and IL-17+ T cells. Notably, the administration of Abs to K1T led to cellular and humoral immune responses to Col-V prior to development of fibrosis, and vice versa, indicating that epitope spreading can occur rapidly in an alloantigen independent manner. Collectively, these data support a model of chronic LTx rejection where the progressive loss of self-tolerance through epitope spreading promotes airway fibrosis. Strategies that target autoreactive Abs may be useful to inhibit chronic rejection of lung grafts.