HMOX1 and pulmonary fibrosis: Indeed, already in the absence of bleomycin dietary quercetin supplementation led to enhanced pulmonary expression of the redox-sensitive transcription factor Nrf2, as well as Nrf2-responsive antioxidant genes including catalase, HO-1 and ƴ-GCS, previously shown to protect against bleomycin-induced pulmonary fibrosis [18, 22, 55].