Pigeon breeder’s disease (PBD) is a granulomatous inflammatory disease of the lung that occurs in people exposed to bird antigens (hypersensitivity pneumonitis). In this and several other diseases, such as idiopathic pulmonary fibrosis (IPF), rheumatoid arthritis, and cancer, there is a change in the balance of proteolysis and antiproteolysis brought about by matrix metalloproteinases (MMPs) …