TGFB1 and pulmonary fibrosis: Spermidine and spermine have inhibited TGF-β–driven fibrogenesis in multiple models [8,29], including bleomycin-induced lung fibrosis, where spermidine promoted autophagy and limited ER-stress apoptosis [8], and kidney fibrosis, where it suppressed TGF-β1 and collagen via Nrf2 activation [29].