Cigarette smoke-initiated autoimmunity facilitates sensitisation to elastin-induced COPD-like pathologies in mice.

It is currently not understood whether cigarette smoke (CS) exposure facilitates sensitisation to self-antigens and whether ensuing auto-reactive T cells drive COPD-associated pathologies. To address this question, mice were exposed to CS for 2 weeks. Following a two-week period of rest, mice were challenged intratracheally with elastin for 3 days or 1 month. Rag1−/−, Mmp12−/−, and Il17a−/− mice and neutralising antibodies against active elastin fragments were used for mechanistic investigations. Human GVAPGVGVAPGV/HLA-A*02:01 tetramer was synthesised to assess the presence of elastin-specific T cells in patients with COPD. We observed that 2 weeks of CS exposure induced an elastin-specific T cell response that led to neutrophilic airway inflammation and mucus hyperproduction following elastin recall challenge. Repeated elastin challenge for 1 month resulted in airway remodelling, lung function decline, and airspace enlargement. Elastin-specific T cell recall responses were dose dependent and memory lasted for over 6 months. Adoptive T cell transfer and studies in T cells deficient Rag1−/−mice conclusively implicated T cells in these processes. Mechanistically, CS exposure induced elastin-specific T cell responses were MMP12-dependent, while the ensuing immune inflammatory processes were IL17A-driven. Anti-elastin antibodies and T cells specific for elastin peptides were increased in patients with COPD. These data demonstrate that MMP12-generated elastin fragments serve as a self-antigen and drive the CS-induced autoimmune processes in mice that result in a bronchitis-like phenotype and airspace enlargement. The study provides proof of concept of CS-induced autoimmune processes and may serve as a novel mouse model of COPD.