Matching what was observed in our reanalysis of the Haberman et al. single-cell database, fibroblasts from patients with IPF showed a significant upregulation of TDO2 following stimulation with the TLR9 ligand ODN2395, while expression of IDO1 was significantly downregulated (Figure 6B). The gene discussed is IDO1; the disease is idiopathic pulmonary fibrosis.