HMOX1 and infection: In line with previous observations, showing upregulation of Fpn, Fth1 and HO-1 in response to iron loading of macrophages [37, 58], infection with Burkholderia downregulates Fpn transcription in both iron- and vehicle-treated macrophages, whereas Fth1 and HO-1 mRNA levels are significantly upregulated by FAC or FeSO4.