Fig. 2: Dysregulation of iron homeostasis contributes to ferroptosis.

a The initial and last serum ferritin level in deceased COVID-19 patient (n = 12) during hospitalization. Gray area represents normal range (11–336 ng/mL). Connected dots represents the same patient. b Severe and mild COVID-19 explant/biopsy, and control cases were IHC stained with anti-TfR1 antibody (clone H68.4) and IF stained with anti-ferritin light chain (FTL) antibody. The positive stain area of TfR1 and mean intensity of FTL are normalized to the non-infected control group. Data shown as mean ± SEM, n = 4 (control), n = 7 (severe), n = 6 (mild) (left panel). n = 6 (control), n = 7 (severe), n = 6 (mild) (right panel). One-way ANOVA (p value indicated). c Reanalysis of single cell RNA sequencing dataset (GEO, GSE171524). Plot shows the scaling relative to each gene’s expression across all cells associated with each column label in the plot. Iron regulatory pathway genes are shown. d UMAP plot shows the expression of FTL and TfR1 across different alveolar cell types in COVID-19 vs. control groups. e Primary lung epithelial cells were treated with 20 mg/mL ferric ammonium citrate (FAC) with or without 10 μM ferrostatin-1 (Fer-1) or 10 μM liproxstatin-1 (Lip-1) for 5 h. Lipid peroxidation was measured by C11-BODIPY^581/591 using flow cytometry. Data shown as representative result of 2 independent experiments. f Primary lung epithelial cells were co-treated with 2 mg/mL FAC with or without 10 μM Lip-1, and the dose responses to RSL3 and IKE at 24 h were measured. Data shown as mean ± SD of n = 3 technical replicates. g Dose response curve of FAC in Calu-1 cells at 24 h with or without 10 μM Fer-1. Data shown as mean ± SD of n = 3 technical replicates. h Western blot analysis of primary lung epithelial cells treated with 20 mg/mL FAC with or without 10 μM Lip-1 for 5 h. Whole cell lysate was collected and 40 μg of protein was loaded to each lane. FTL and α-Tubulin were blotted. Data shown as representative result of 2 independent experiments. Uncropped blots are provided in Supplementary Fig. 6.