Pulmonary Angiogenesis in a Rat Model of Hepatopulmonary Syndrome

Junlan Zhang, Bao Luo, Liping Tang, Yongming Wang, Cecil R. Stockard, Inga Kadish, Thomas Van Groen, William E. Grizzle, Selvarangan Ponnazhagan, Michael B. Fallon

Research output: Contribution to journalArticle

120 Scopus citations

Abstract

Background & Aims: Hepatopulmonary syndrome (HPS), defined as intrapulmonary vasodilation, occurs in 10%-30% of cirrhotics and increases mortality. In a rat model of HPS induced by common bile duct ligation (CBDL), but not thioacetamide (TAA)-induced nonbiliary cirrhosis, lung capillary density increases, monocytes accumulate in the microvasculature, and signaling factors in the angiogenesis pathway (Akt and endothelial nitric oxide synthase [eNOS]) are activated. Pentoxifylline (PTX) directly decreases lung endothelial Akt and eNOS activation, blocks intravascular monocyte accumulation, and improves experimental HPS; we evaluated whether pulmonary angiogenesis develops in this model. Methods: TAA- and PTX-treated animals were evaluated following CBDL. Lung angiogenesis was assessed by quantifying factor VIII-positive microvessels and levels of von Willebrand factor (vWf), vascular endothelial cadherin (VE-cadherin), and proliferating cell nuclear antigen (PCNA). Angiogenic factors including phospho-Akt, phospho-eNOS, vascular endothelial growth factor (VEGF)-A, and phospho-VEGF receptor-2 (p-VEGFR-2) were compared and monocyte accumulation was assessed. Results: Following CBDL, but not TAA exposure, rats developed HPS that was temporally correlated with increased numbers of lung microvessel; increased levels of vWf, VE-cadherin and PCNA; and activation of Akt and eNOS. Angiogenesis was accompanied by increased pulmonary VEGF-A and p-VEGFR-2 levels, with VEGF-A staining in accumulated intravascular monocytes and alveolar endothelial cells. Following CBDL, PTX-treated rats had reduced numbers of microvessels, reduced lung monocyte accumulation, downregulation of pulmonary angiogenic factors, and reduced symptoms of HPS. Conclusions: A specific increase in pulmonary angiogenesis occurs as experimental HPS develops, accompanied by activation of VEGF-A-associated angiogenic pathways. PTX decreases the angiogenesis, reduces the symptoms of HPS, and downregulates VEGF-A mediated pathways.

Original languageEnglish (US)
Pages (from-to)1070-1080
Number of pages11
JournalGastroenterology
Volume136
Issue number3
DOIs
StatePublished - Mar 2009

ASJC Scopus subject areas

  • Hepatology
  • Gastroenterology

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    Zhang, J., Luo, B., Tang, L., Wang, Y., Stockard, C. R., Kadish, I., Van Groen, T., Grizzle, W. E., Ponnazhagan, S., & Fallon, M. B. (2009). Pulmonary Angiogenesis in a Rat Model of Hepatopulmonary Syndrome. Gastroenterology, 136(3), 1070-1080. https://doi.org/10.1053/j.gastro.2008.12.001