pulmonary fibrosis lung transplantinterstitial fibrosis lungnitrofurantoin pulmonary fibrosismethotrexate pulmonary fibrosisprogressive pulmonary fibrosispulmonary fibrosis prognosisidiopathic lung fibrosissevere pulmonary fibrosischronic pulmonary fibrosisdefine pulmonary fibrosisbleomycin pulmonary fibrosisfamilial pulmonary fibrosis