Transgenic expression of human matrix metalloproteinase-9 augments monocrotaline-induced pulmonary arterial hypertension in mice.
OBJECTIVE
Pulmonary arterial hypertension (PAH) is characterized by intimal lesions, right ventricular hypertrophy, and adventitial thickening of pulmonary arteries with progressive pulmonary hypertension. This investigation was aimed to examine the effects of transgenic expression of human matrix metalloproteinase-9 (MMP-9) in the pathogenesis of PAH.


METHODS
PAH was induced using serial subcutaneous administration of monocrotaline (MCT). Right ventricular pressure was measured through the right jugular vein using a 1.4F Millar Mikro-tip catheter-transducer. Zymography, western blotting, and quantitative reverse transcription PCR (qRT-PCR) were carried out for MMP-9. Immunohistochemistry was performed for α-smooth muscle actin (α-SMA) and Mac-3 antigen.


RESULTS
Measurement of right ventricular pressure demonstrated 2.5-fold and 3.7-fold elevation after the administration of MCT in wild-type and MMP-9 transgenic mice, respectively. Zymography, western blotting, and qRT-PCR depicted increased activity and expression of MMP-9 after treatment with MCT, which were augmented in transgenic mice. There was marked pulmonary inflammation with extensive infiltration of mononuclear cells, which was more intense in MMP-9 transgenic mice. SMA and Mac-3 staining demonstrated hypertrophy of pulmonary arteries with occlusion of precapillary vessels and extensive infiltration of macrophages, respectively. All these changes were aggravated in MCT-treated MMP-9 transgenic mice when compared to normal littermates.


CONCLUSIONS
Our study demonstrated that the MCT-induced PAH in mouse is a reproducible and potentially valuable animal model for the human disease. Our results further demonstrated that MMP-9 plays a significant role in the pathogenesis of PAH and effective blocking of MMP-9 could provide an option in the therapeutic intervention of human PAH.
Division of Molecular Medicine, Department of Medicine, Columbia University, New York, New York, USA. jgeorge40@hotmail.com
Joseph
J
George
Jeanine
J
D'Armiento
D000199:Actins / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D001483:Base Sequence; D001794:Blood Pressure; D017931:DNA Primers / Q000235:genetics; D004195:Disease Models, Animal; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D006976:Hypertension, Pulmonary / Q000201:enzymology* / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics* / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D016686:Monocrotaline / Q000633:toxicity*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D000199:Actins; D000943:Antigens, Differentiation; D017931:DNA Primers; D012333:RNA, Messenger; D011994:Recombinant Proteins; C544013:alpha-smooth muscle actin, mouse; C036763:monocyte-macrophage differentiation antigen; D016686:Monocrotaline; D020780:Matrix Metalloproteinase 9