TGFB1 and idiopathic pulmonary fibrosis: On the other hand, LRP5 affected TGF-β1 levels, as our results showed that renal levels of total TGF-β1 were reduced in Lrp5−/− UUO kidneys, which was consistent with decreased total TGF-β1 production in IPF.5 It is not well understood how LRP5 affects total TGF-β1 levels in these fibrotic diseases.