Figure 1.

Loss of CD68+ (cluster of differentiation) macrophages does not protect against hypoxia-induced PH: macrophage low (MacLow) mice were fed either doxycycline-containing diet or normal laboratory diet for 2 wk to induce macrophage ablation, and then PH was induced by hypoxia (10% oxygen) for another 2 wk with continuous doxycycline diet. Parallel groups were left in normal air as controls. A, Experimental timeline. B, Quantification of F4/80+ macrophages remaining within the liver after 4-wk doxycycline treatment. C–E, Assessment of PH phenotype with right ventricular (RV) end-systolic pressure (RVESP; C), RV hypertrophy (RVH) index (D), and medial wall thickness as a ratio of total vessel size (media/cross-sectional area [CSA]; E). F–H, Quantification of macrophages remaining within the lung after 4-wk doxycycline treatment using anti-F4/80 antibody for total macrophages (F), anti-iNOS (inducible NO synthase) antibody for M1 macrophages (G), and anti-CD206 antibody for M2 macrophages (H). I, Representative photomicrographs of liver sections immunostained for F4/80 and lung sections immunostained for F4/80 and αSMA (α-smooth muscle actin) or stained with Alcian blue Elastic van Gieson (ABEVG). n=6 to 10/group. Bars show mean±SEM. Hypoxia, 10% oxygen; normoxia, 21% oxygen. ♂, male mice; ♀, female mice. Scale bar=50 µm. LV&S indicates left ventricular free wall plus septum. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001.