Figure 6.

Proapoptotic and antiproliferative effects of TAM (Tyro3, Axl, and Mertk) receptor inhibitors in normal and IPF fibroblasts. (A and B) Fibroblast cultures derived from normal and IPF lungs were treated with the small-molecule inhibitors R428 (2 and 10 μM) and LDC (5 and 25 μM) or vehicle; and the antibodies S6 (4 μg/ml), anti-Axl (20 μg/ml), or IgG (20 μg/ml). Caspase-3 activity was evaluated after treatment with (A) small-molecule inhibitors or (B) the antibodies. FasL (75 ng/ml) plus His-Tag cross-linking antibody (5 μg/ml) was added to other cultures of fibroblasts for 18 hours. Data are mean ± SEM, n = 3–4 per group. *P ≤ 0.05, ***P ≤ 0.001. (C) Representative images from normal and IPF fibroblasts treated with R428 (10 μM) or vehicle in the presence or absence of FasL for 18 hours. (D) Cell proliferation was assessed for 18 hours according to the percentage of cell confluence using IncuCyte ZOOM software. Data are representative findings from a normal and IPF fibroblast line that were tested under the conditions described previously. Data from additional normal (n = 3) and IPF (n = 4) fibroblast lines are shown in Figure E3. Scale bars in C are 300 μm. Data in D are mean ±  SEM. α-Axl = anti-Axl; Axl = anexelekto; IPF = idiopathic pulmonary fibrosis; LDC = LDC1267; Mertk = MER proto-oncogene, tyrosine kinase; RFU = relative fluorescent units; Tyro3 = TYRO3 protein tyrosine kinase 3.