Expression of VEGF and its receptors Flt-1 and Flk-1/KDR is altered in lambs with increased pulmonary blood flow and pulmonary hypertension.
Utilizing in utero aortopulmonary vascular graft placement, we developed a lamb model of congenital heart disease and increased pulmonary blood flow. We showed previously that these lambs have increased pulmonary vessel number at 4 wk of age. To determine whether this was associated with alterations in VEGF signaling, we investigated vascular changes in expression of VEGF and its receptors, Flt-1 and KDR/Flk-1, in the lungs of shunted and age-matched control lambs during the first 8 wk of life. Western blot analysis demonstrated that VEGF, Flt-1, and KDR/Flk-1 expression was higher in shunted lambs. VEGF and Flt-1 expression was increased at 4 and 8 wk of age (P <0.05). However, KDR/Flk-1 expression was higher in shunted lambs only at 1 and 4 wk of age (P <0.05). Immunohistochemical analysis demonstrated that, in control and shunted lambs, VEGF localized to the smooth muscle layer of vessels and airways and to the pulmonary epithelium while increased VEGF expression was localized to the smooth muscle layer of thickened media in remodeled vessels in shunted lambs. VEGF receptors were localized exclusively in the endothelium of pulmonary vessels. Flt-1 was increased in the endothelium of small pulmonary arteries in shunted animals at 4 and 8 wk of age, whereas KDR/Flk-1 was increased in small pulmonary arteries at 1 and 4 wk of age. Our data suggest that increased pulmonary blood flow upregulates expression of VEGF and its receptors, and this may be important in development of the vascular remodeling in shunted lambs.
Mata-Greenwood
Eugenia
E
Department of Pediatrics, Northwestern University, Chicago, Illinois 60611-3008, USA.
Meyrick
Barbara
B
Soifer
Scott J
SJ
Fineman
Jeffrey R
JR
Black
Stephen M
SM
D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D016228:Endothelial Growth Factors / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D005260:Female; D006976:Hypertension, Pulmonary / Q000378:metabolism* / Q000503:physiopathology; D015151:Immunoblotting; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008168:Lung / Q000098:blood supply / Q000378:metabolism; D008222:Lymphokines / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011247:Pregnancy; D011652:Pulmonary Circulation / Q000502:physiology*; D011817:Rabbits; D012756:Sheep; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2