Figure 7: Altered epithelial barrier structure and function in Stard7epi∆/∆ mice.
(a) Epithelial barrier permeability was assessed by tail vein injection of FITC-albumin, followed by quantitation of FITC in BALF and serum from Stard7f/f and Stard7epi∆/∆ mice. Results are expressed as BALF FITC/Serum FITC, n = 8–10 mice/group. Stard7f/f mice vs. Stard7epi∆/∆ mice, ***p = 0.0001. (b) SEM detected surface fractures between bronchiolar epithelial cells (asterisk) and club cells (C) in Stard7epi∆/∆ mice. (c) Fixed mouse lungs were cut into 1–2 mm lung slices, incubated with 2% lanthanum nitrate at room temperature overnight, and processed for electron microscopy. Penetration of electron dense lanthanum nitrate into the intercellular spaces (arrow) was detected in the airway epithelium of Stard7epi∆/∆ mice. G: Golgi, MT: mitochondria, NUC: Nucleus. (d) Tracheal epithelial cells were isolated from Stard7epi∆/∆ and Stard7f/f mice and cultured until TEER >220/cm2. Cells were subsequently differentiated at an air-liquid interface for 3 weeks and treated with/without MitoTEMPO (5 μM) every other day. Paracellular flux of FITC-dextran was measured over a 3 hr period. Stard7epi/∆∆ vs. Stard7epi∆/∆ + MitoTEMPO, *p = 0.0311, **p = 0.0106, ***p < 0.001; Stard7epi∆/∆ vs. Stard7f/f, *p = 0.0201, **p = 0.0091, ***p < 0.001.
