Expression of vascular endothelial growth factor and its receptors correlates closely with formation of the plexiform lesion in human pulmonary hypertension
S. Hirose et al., Expression of vascular endothelial growth factor and its receptors correlates closely with formation of the plexiform lesion in human pulmonary hypertension, PATHOL INT, 50(6), 2000, pp. 472-479
The pulmonary vasculature exhibits various morphological changes in patient
s with pulmonary hypertension (PH). Among them, the plexiform lesion is one
of the most characteristic vascular lesions, although nothing is known abo
ut the molecular mechanisms of its formation. In the present study, the exp
ression of vascular endothelial growth factor (VEGF), an endothelial cell-s
pecific angiogenic mitogen, and its receptors, fms-like tyrosine kinase (Fl
t-1) and kinase insert domain-containing receptor (KDR), in the lungs of fi
ve cases with PH, were examined. By in situ hybridization, VEGF expression
was found in modified smooth muscle cells inside the plexiform lesions as w
ell as in medial smooth muscle cells of the arteries adjacent to the lesion
s. The expression of Flt-1 mRNA was observed in endothelial cells of the ar
teries adjacent to the plexiform lesions, while KDR mRNA was expressed in t
he endothelial cells inside the plexiform lesions. VEGF was immunolocalized
to the endothelial cells expressing its receptors as well as the modified
smooth muscle cells producing VEGF. These results demonstrate that VEGF and
its receptors are upregulated with a close correlation to the plexiform le
sions, and suggest that VEGF expressed by smooth muscle cells may activate
the endothelial cells to form the plexiform lesions.