Non-stimulated primary human lung fibroblasts isolated from IPF lungs had increased expression of pro-fibrotic markers (collagen and fibronectin), markers of activation (α-SMA and Nox4), and a slight higher expression of TLR9 (1.5-fold) compared to fibroblasts isolated from aged-matched non-IPF controls (IPF = 67±3 y; Control = 68±4 y) (Fig 7B). Here, NOX4 is linked to idiopathic pulmonary fibrosis.