Abstract 18375: Inflammatory Macrophage Expansion in Pulmonary Hypertension Depends Upon Mobilization of Blood-borne Monocytes

Introduction: Pulmonary inflammation has been proposed as a key pathogenic driver of pulmonary hypertension (PH), vascular disease with increasing global significance. Perivascular macrophages have been observed in the lungs of PH patients. However, the mechanisms of expansion of lung macrophages and the role of blood-borne monocytes in PH are poorly understood. Hypothesis: We hypothesize that increased monocyte recruitment and differentiation in the lungs augment inflammatory macrophage content and vascular remodeling in PH. Methods: We recapitulated PH in both hypoxic mouse and monocrotaline injected rat models. We enumerated blood and lung myeloid cell populations in mouse and rat as well as in PH patients using multicolor flow cytometric analysis. To track the origin of lung macrophages, we surgically joined congenically different hypoxic mice (parabiosis). To evaluate the importance of monocyte recruitment to the lungs we reduced monocyte number in two separate rodent models of PH - via genetic defic...