CD14 and pulmonary arterial hypertension: Monocrotaline (MCT) PAH rats have increased intestinal permeability as measured by fluorescein isothiocyanate (FITC)-dextran, lipopolysaccharide (LPS), and soluble CD14 in the blood [24] and disrupted intestinal morphology, with greater muscularis layer thickness and fibrosis and diminished villus length and goblet cell number [21,25].